Integrated hydrocracking and dewaxing of hydrocarbons

ABSTRACT

An integrated process for producing naphtha fuel, diesel fuel and/or lubricant base oils from feedstocks under sour conditions is provided. The ability to process feedstocks under higher sulfur and/or nitrogen conditions allows for reduced cost processing and increases the flexibility in selecting a suitable feedstock. The sour feed can be delivered to a catalytic dewaxing step without any separation of sulfur and nitrogen contaminants. The integrated process includes an initial dewaxing of a feed under sour conditions, optional hydrocracking of the dewaxed feed, and a separation to form a first diesel product and a bottoms fraction. The bottoms fraction is then exposed to additional hydrocracking and dewaxing to form a second diesel product and optionally a lubricant base oil product. Alternatively, a feedstock can be hydrotreated, fractionated, dewaxed, and then hydrocracked to form a diesel fuel and a dewaxed, hydrocracked bottoms fraction that is optionally suitable for use as a lubricant base oil.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a non-provisional application that claims priority to U.S.Provisional Patent Application No. 61/359,571 filed on Jun. 29, 2010,herein incorporated by reference in its entirety.

FIELD

This disclosure provides a system and a method for processing of sulfur-and/or nitrogen-containing feedstocks to produce diesel fuels andlubricating oil basestocks.

BACKGROUND

Hydrocracking of hydrocarbon feedstocks is often used to convert lowervalue hydrocarbon fractions into higher value products, such asconversion of vacuum gas oil (VGO) feedstocks to diesel fuel andlubricants. Typical hydrocracking reaction schemes can include aninitial hydrotreatment step, a hydrocracking step, and a posthydrotreatment step. After these steps, the effluent can be fractionatedto separate out a desired diesel fuel and/or lubricant oil basestock.

One method of classifying lubricating oil basestocks is that used by theAmerican Petroleum Institute (API). API Group II basestocks have asaturates content of 90 wt % or greater, a sulfur content of not morethan 0.03 wt % and a VI greater than 80 but less than 120. API Group IIIbasestocks are the same as Group II basestocks except that the VI is atleast 120. A process scheme such as the one detailed above is typicallysuitable for production of Group II and Group III basestocks from anappropriate feed.

U.S. Pat. No. 6,884,339 describes a method for processing a feed toproduce a lubricant base oil and optionally distillate products. A feedis hydrotreated and then hydrocracked without intermediate separation.An example of the catalyst for hydrocracking can be a supported Y orbeta zeolite. The catalyst also includes a hydro-dehydrogenating metal,such as a combination of Ni and Mo. The hydrotreated, hydrocrackedeffluent is then atmospherically distilled. The portion boiling above340° C. is catalytically dewaxed in the presence of a bound molecularsieve that includes a hydro-dehydrogenating element. The molecular sievecan be ZSM-48, EU-2, EU-11, or ZBM-30. The hydro-dehydrogenating elementcan be a noble Group VIII metal, such as Pt or Pd.

U.S. Pat. No. 7,371,315 describes a method for producing a lubricantbase oil and optionally distillate products. A feed is provided with asulfur content of less than 1000 wppm. Optionally, the feed can be ahydrotreated feed. Optionally, the feed can be a hydrocracked feed, suchas a feed hydrocracked in the presence of a zeolite Y-containingcatalyst. The feed is converted on a noble metal on an acidic support.This entire converted feed can be dewaxed in the presence of a dewaxingcatalyst.

U.S. Pat. No. 7,300,900 describes a catalyst and a method for using thecatalyst to perform conversion on a hydrocarbon feed. The catalystincludes both a Y zeolite and a zeolite selected from ZBM-30, ZSM-48,EU-2, and EU-11. Examples are provided of a two stage process, with afirst stage hydrotreatment of a feed to reduce the sulfur content of thefeed to 15 wppm, followed by hydroprocessing using the catalystcontaining the two zeolites. An option is also described where itappears that the effluent from a hydrotreatment stage is cascadedwithout separation to the dual-zeolite catalyst, but no example isprovided of the sulfur level of the initial feed for such a process.

SUMMARY

In an embodiment, a method is provided for producing a naphtha fuel, adiesel fuel, and a lubricant basestock. The method includes contacting ahydrotreated feedstock with a hydrocracking catalyst under firsteffective hydrocracking conditions to produce a hydrocracked effluent.The hydrotreated feedstock is cascaded to the hydrocracking catalystwithout intermediate separation. The entire hydrocracked effluent iscascaded, without separation, to a catalytic dewaxing stage. The entirehydrocracked effluent is dewaxed under first effective catalyticdewaxing conditions in the presence of a dewaxing catalyst. The dewaxingcatalyst includes at least one non-dealuminated, unidimensional,10-member ring pore zeolite, and at least one Group VI metal, Group VIIImetal or combination thereof. Optionally, the dewaxing catalyst caninclude at least one low surface area metal oxide, refractory binder.The combined total sulfur in liquid and gaseous forms fed to thedewaxing stage is greater than 1000 ppm by weight of sulfur on ahydrotreated feedstock basis. The dewaxed effluent is fractionated toproduce at least a naphtha product fraction, a first diesel productfraction, and a bottoms fraction. The bottoms fraction is hydrocrackedunder second effective hydrocracking conditions. The bottoms fraction isalso dewaxed under second effective catalytic dewaxing conditions. Thedewaxing of the bottoms fraction can occur prior to hydrocracking, afterhydrocracking, or both prior to and after hydrocracking. Thehydrocracked, dewaxed bottoms fraction is fractionated to form at leasta second diesel product fraction and a lubricant base oil productfraction.

In another embodiment, a method for producing a diesel fuel and alubricant basestock is provided. The method includes contacting ahydrotreated feedstock with a dewaxing catalyst under first effectivedewaxing conditions to produce a dewaxed effluent. The dewaxing catalystincludes at least one non-dealuminated, unidimensional, 10-member ringpore zeolite, and at least one Group VI metal, Group VIII metal orcombination thereof. Optionally, the dewaxing catalyst can include atleast one low surface area metal oxide, refractory binder. Thehydrotreated feedstock is cascaded to the dewaxing catalyst withoutintermediate separation. The dewaxed effluent is fractionated to produceat least a first diesel product fraction and a bottoms fraction. Thebottoms fraction is hydrocracked under first effective hydrocrackingconditions. The bottoms fraction is also dewaxed under second effectivecatalytic dewaxing conditions. The hydrocracked, dewaxed bottomsfraction is fractionated to form at least a second diesel productfraction and a lubricant base oil product fraction.

In still another embodiment, a method for producing a diesel fuel and alubricant basestock is provided. The method includes contacting afeedstock with a hydrotreating catalyst under first effectivehydrotreating conditions to produce a hydrotreated effluent. Thehydrotreated effluent is fractionated to produce at least a first dieselproduct fraction and a bottoms fraction. The bottoms fraction is dewaxedunder effective catalytic dewaxing conditions, the dewaxing catalystincludes at least one non-dealuminated, unidimensional, 10-member ringpore zeolite, and at least one Group VI metal, Group VIII metal, orcombination thereof. Optionally, the dewaxing catalyst can include atleast one low surface area metal oxide, refractory binder. The bottomsfraction is also hydrocracked under effective hydrocracking conditions.The hydrocracked, dewaxed bottoms fraction is fractionated to form atleast a second diesel product fraction and a lubricant base oil productfraction.

In still yet another embodiment, a method for producing a diesel fueland a lubricant basestock is provided. The method includes contacting afeedstock with a hydrotreating catalyst under effective hydrotreatingconditions to produce a hydrotreated effluent; fractionating thehydrotreated effluent to produce at least a first diesel productfraction and a bottoms fraction; hydrocracking the bottoms fractionunder effective hydrocracking conditions; dewaxing the bottoms fractionunder effective catalytic dewaxing conditions, the dewaxing catalystincluding at least one non-dealuminated, unidimensional, 10-member ringpore zeolite, and at least one Group VI metal, Group VIII metal orcombination thereof; and fractionating the hydrocracked, dewaxed bottomsfraction to form at least a second diesel product fraction and alubricant base oil product fraction.

In still yet another embodiment, a method for producing a diesel fueland a lubricant basestock is provided. The method includes contacting afeedstock with a hydrotreating catalyst under effective hydrotreatingconditions to produce a hydrotreated effluent; fractionating thehydrotreated effluent to produce at least a first diesel productfraction and a first bottoms fraction; dewaxing the bottoms fractionunder effective catalytic dewaxing conditions, the dewaxing catalystincluding at least one non-dealuminated, unidimensional, 10-member ringpore zeolite, and at least one Group VI metal, Group VIII metal orcombination thereof; fractionating the dewaxed bottoms fraction to format least a second diesel product fraction and a second bottoms fraction;hydrocracking the second bottoms fraction under effective hydrocrackingconditions to form a third bottoms fraction; and fractionating the thirdbottoms fraction to form at least a naphtha product fraction, a dieselproduct fraction and a lubricant base oil product fraction.

In still yet another embodiment, a method for producing a diesel fueland a lubricant basestock is provided. The method includes contacting afeedstock with a hydrotreating catalyst under effective hydrotreatingconditions to produce a hydrotreated effluent; fractionating thehydrotreated effluent to produce at least a first diesel productfraction and a first bottoms fraction; hydrocracking the first bottomsfraction under effective hydrocracking conditions to form a secondbottoms fraction; fractionating the second bottoms fraction to form atleast a second diesel product fraction and a third bottoms fraction;dewaxing at least a portion of the third bottoms fraction undereffective catalytic dewaxing conditions, the dewaxing catalyst includingat least one non-dealuminated, unidimensional, 10-member ring porezeolite, and at least one Group VI metal, Group VIII metal orcombination thereof; and fractionating the dewaxed third bottomsfraction and the non-dewaxed third bottoms fraction to form at least anaphtha product fraction, a third diesel product fraction and alubricant base oil product fraction.

In still yet another embodiment, a method is provided for producing anaphtha fuel, a diesel fuel, and a lubricant basestock. The methodincludes contacting a hydrotreated feedstock with a hydrocrackingcatalyst under first effective hydrocracking conditions to produce ahydrocracked effluent. The hydrotreated feedstock is cascaded to thehydrocracking catalyst without intermediate separation. The entirehydrocracked effluent is cascaded, without separation, to a catalyticdewaxing stage. The entire hydrocracked effluent is dewaxed under firsteffective catalytic dewaxing conditions in the presence of a dewaxingcatalyst. The dewaxing catalyst includes at least one non-dealuminated,unidimensional, 10-member ring pore zeolite, and at least one Group VImetal, Group VIII metal or combination thereof. Optionally, the dewaxingcatalyst can include at least one low surface area metal oxide,refractory binder. The combined total sulfur in liquid and gaseous formsfed to the dewaxing stage is greater than 1000 ppm by weight of sulfuron a hydrotreated feedstock basis. The dewaxed effluent is fractionatedto produce at least a naphtha product fraction, a first diesel productfraction, and a bottoms fraction. The bottoms fraction is hydrocrackedunder second effective hydrocracking conditions. The bottoms fraction isalso dewaxed under second effective catalytic dewaxing conditions. Thedewaxing of the bottoms fraction can occur prior to hydrocracking, afterhydrocracking, or both prior to and after hydrocracking. Thehydrocracked, dewaxed bottoms fraction is fractionated to form at leasta second diesel product fraction and a lubricant base oil productfraction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an example of a multi-stage reaction systemaccording to an embodiment of the invention.

FIG. 2 schematically shows examples of catalyst configurations for afirst reaction stage.

FIG. 3 schematically shows examples of catalyst configurations for asecond reaction stage.

FIG. 4 shows predicted diesel fuel product yields for various processingconfigurations.

FIGS. 5 and 6 show measured feed conversion and diesel fuel productyields for various processing configurations.

FIG. 7 schematically shows an example of a three-stage reaction systemaccording to an alternative embodiment of the invention.

FIG. 8 schematically shows an example of a four-stage reaction systemaccording to an alternative embodiment of the invention.

FIG. 9 schematically shows an example of a still yet another three-stagereaction system according to an alternative embodiment of the invention.

DETAILED DESCRIPTION

All numerical values within the detailed description and the claimsherein are modified by “about” or “approximately” the indicated value,and take into account experimental error and variations that would beexpected by a person having ordinary skill in the art.

Overview

One option for processing a heavier feed, such as a heavy distillate orgas oil type feed, is to use hydrocracking to convert a portion of thefeed. Portions of the feed that are converted below a specified boilingpoint, such as a 700° F. (371° C.) portion that can be used for naphthaand diesel fuel products, while the remaining unconverted portions canbe used as lubricant oil basestocks.

Improvements in diesel and/or lube basestock yield can be based in parton alternative configurations that are made possible by use of adewaxing catalyst. For example, zeolite Y based hydrocracking catalystsare selective for cracking of cyclic and/or branched hydrocarbons.Paraffinic molecules with little or no branching may require severehydrocracking conditions in order to achieve desired levels ofconversion. This can result in overcracking of the cyclic and/or moreheavily branched molecules in a feed. A catalytic dewaxing process canincrease the branching of paraffinic molecules. This can increase theability of a subsequent hydrocracking stage to convert the paraffinicmolecules with increased numbers of branches to lower boiling pointspecies.

In various embodiments, a dewaxing catalyst can be selected that issuitable for use in a sweet or sour environment while minimizingconversion of higher boiling molecules to naphtha and other lessvaluable species. The dewaxing catalyst can be used as part of anintegrated process in a first stage that includes an initialhydrotreatment of the feed, hydrocracking of the hydrotreated feed, anddewaxing of the effluent from the hydrocracking, and an optional finalhydrotreatment. Alternatively, the dewaxing stage can be performed onthe hydrotreated feed prior to hydrocracking. Optionally, thehydrocracking stage can be omitted. The treated feed can then befractionated to separate out the portions of the feed that boil below aspecified temperature, such as below 700° F. (371° C.).

A second stage can then be used to process the unconverted bottoms fromthe fractionator. The bottoms fraction can be hydrocracked for furtherconversion, optionally hydrofinished, and optionally dewaxed.

In a conventional scheme, any catalytic dewaxing and/orhydroisomerization is performed in a separate reactor. This is due tothe fact conventional catalysts are poisoned by the heteroatomcontaminants (such as H₂S NH₃, organic sulfur and/or organic nitrogen)typically present in the hydrocracker effluent. Thus, in a conventionalscheme, a separation step is used to first decrease the amount of theheteroatom contaminants. Because a distillation also needs to beperformed to separate various cuts from the hydrocracker effluent, theseparation may be performed at the same time as distillation, andtherefore prior to dewaxing. This means that some valuable hydrocarbonmolecules that could be used in a diesel or lube basestock cut are leftout.

In various embodiments, a layer of dewaxing catalyst can be includedafter a hydrotreating and/or hydrocracking step in the first stage,without the need for a separation stage. By using a contaminant tolerantcatalyst, a mild dewaxing step can be performed on the entirehydrotreated, hydrocracked, or hydrotreated and hydrocracked effluent.This means that all molecules present in the effluent are exposed tomild dewaxing. This mild dewaxing will modify the boiling point oflonger chain molecules, thus allowing molecules that would normally exita distillation step as bottoms to be converted to molecules suitable forlubricant basestock. Similarly, some molecules suitable for lubricantbasestock will be converted to diesel range molecules.

By having a dewaxing step in the first sour stage, the cold flowproperties of the effluent from the first stage can be improved. Thiscan allow a first diesel product to be generated from the fractionationafter the first stage. Producing a diesel product from the fractionationafter the first stage can provide one or more advantages. This can avoidfurther exposure of the first diesel product to hydrocracking, andtherefore reduces the amount of naphtha generated relative to diesel.Removing a diesel product from the fractionator after the first stagealso reduces the volume of effluent that is processed in the second orlater stages. Still another advantage can be that the bottoms productfrom the first stage has an improved quality relative to a first stagewithout dewaxing functionality. For example, the bottoms fraction usedas the input for the second stage can have improved cold flowproperties. This can reduce the severity needed in the second stage toachieve a desired product specification.

The second stage can be configured in a variety of ways. One option canbe to emphasize diesel production. In this type of option, a portion ofthe unconverted bottoms from the second stage can be recycled to thesecond stage. This can optionally be done to extinction, to maximizediesel production. Alternatively, the second stage can be configured toproduce at least some lubricant base stock from the bottoms.

Still another advantage can be the flexibility provided by someembodiments. Including a dewaxing capability in both the first stage andthe second stage can allow the process conditions to be selected basedon desired products, as opposed to selecting conditions to protectcatalysts from potential poisoning.

The dewaxing catalysts used according to the invention can provide anactivity advantage relative to conventional dewaxing catalysts in thepresence of sulfur feeds. In the context of dewaxing, a sulfur feed canrepresent a feed containing at least 100 ppm by weight of sulfur, or atleast 1000 ppm by weight of sulfur, or at least 2000 ppm by weight ofsulfur, or at least 4000 ppm by weight of sulfur, or at least 40,000 ppmby weight of sulfur. The feed and hydrogen gas mixture can includegreater than 1,000 ppm by weight of sulfur or more, or 5,000 ppm byweight of sulfur or more, or 15,000 ppm by weight of sulfur or more. Inyet another embodiment, the sulfur may be present in the gas only, theliquid only or both. For the present disclosure, these sulfur levels aredefined as the total combined sulfur in liquid and gas forms fed to thedewaxing stage in parts per million (ppm) by weight on the hydrotreatedfeedstock basis.

This advantage can be achieved by the use of a catalyst comprising a10-member ring pore, one-dimensional zeolite in combination with a lowsurface area metal oxide refractory binder, both of which are selectedto obtain a high ratio of micropore surface area to total surface area.Alternatively, the zeolite has a low silica to alumina ratio. As anotheralternative, the catalyst can comprise an unbound 10-member ring pore,one-dimensional zeolite. The dewaxing catalyst can further include ametal hydrogenation function, such as a Group VI or Group VIII metal,and preferably a Group VIII noble metal. Preferably, the dewaxingcatalyst is a one-dimensional 10-member ring pore catalyst, such asZSM-48 or ZSM-23.

The external surface area and the micropore surface area refer to oneway of characterizing the total surface area of a catalyst. Thesesurface areas are calculated based on analysis of nitrogen porosimetrydata using the BET method for surface area measurement. (See, forexample, Johnson, M. F. L., Jour. Catal., 52, 425 (1978).) The microporesurface area refers to surface area due to the unidimensional pores ofthe zeolite in the dewaxing catalyst. Only the zeolite in a catalystwill contribute to this portion of the surface area. The externalsurface area can be due to either zeolite or binder within a catalyst.

Feedstocks

A wide range of petroleum and chemical feedstocks can be hydroprocessedin accordance with the present invention. Suitable feedstocks includewhole and reduced petroleum crudes, atmospheric and vacuum residua,propane deasphalted residua, e.g., brightstock, cycle oils, FCC towerbottoms, gas oils, including atmospheric and vacuum gas oils and cokergas oils, light to heavy distillates including raw virgin distillates,hydrocrackates, hydrotreated oils, dewaxed oils, slack waxes,Fischer-Tropsch waxes, raffinates, and mixtures of these materials.Typical feeds would include, for example, vacuum gas oils boiling up toabout 593° C. (about 1100° F.) and usually in the range of about 350° C.to about 500° C. (about 660° F. to about 935° F.) and, in this case, theproportion of diesel fuel produced is correspondingly greater. In someembodiments, the sulfur content of the feed can be at least 100 ppm byweight of sulfur, or at least 1000 ppm by weight of sulfur, or at least2000 ppm by weight of sulfur, or at least 4000 ppm by weight of sulfur,or at least 40,000 ppm by weight of sulfur.

Note that for stages that are tolerant of a sour processing environment,a portion of the sulfur in a processing stage can be sulfur containingin a hydrogen treat gas stream. This can allow, for example, an effluenthydrogen stream from a hydroprocessing reaction that contains H₂S as animpurity to be used as a hydrogen input to a sour environment processwithout removal of some or all of the H₂S. The hydrogen streamcontaining H₂S as an impurity can be a partially cleaned recycledhydrogen stream from one of the stages of a process according to theinvention, or the hydrogen stream can be from another refinery process.

Process Flow Schemes

In the discussion below, a stage can correspond to a single reactor or aplurality of reactors. Optionally, multiple parallel reactors can beused to perform one or more of the processes, or multiple parallelreactors can be used for all processes in a stage. Each stage and/orreactor can include one or more catalyst beds containing hydroprocessingcatalyst. Note that a “bed” of catalyst in the discussion below canrefer to a partial physical catalyst bed. For example, a catalyst bedwithin a reactor could be filled partially with a hydrocracking catalystand partially with a dewaxing catalyst. For convenience in description,even though the two catalysts may be stacked together in a singlecatalyst bed, the hydrocracking catalyst and dewaxing catalyst can eachbe referred to conceptually as separate catalyst beds.

A variety of process flow schemes are available according to variousembodiments of the invention. In one example, a feed can initially byhydrotreated by exposing the feed to one or more beds of hydrotreatmentcatalyst. The entire hydrotreated feed, without separation, can then behydrocracked in the presence of one or more beds of hydrocrackingcatalyst. The entire hydrotreated, hydrocracked feed, withoutseparation, can then be dewaxed in the presence of one or more beds ofdewaxing catalyst. An optional second hydrotreatment catalyst bed canalso be included after either the hydrocracking or the dewaxingprocesses. By performing hydrotreating, hydrocracking, and dewaxingprocesses without an intermediate separation, the equipment required toperform these processes can be included in a single stage.

In another example, a feed can initially by hydrotreated by exposing thefeed to one or more beds of hydrotreatment catalyst. The entirehydrotreated feed, without separation, can then be dewaxed in thepresence of one or more beds of dewaxing catalyst. The entirehydrotreated, dewaxed feed, without separation, can then optionally behydrocracked in the presence of one or more beds of hydrocrackingcatalyst. An optional second hydrotreatment catalyst bed can also beincluded. By performing hydrotreating, dewaxing, and hydrocrackingprocesses without an intermediate separation, the equipment required toperform these processes can be included in a single stage.

After the hydrotreating, dewaxing, and/or hydrocracking in a sourenvironment, the hydroprocessed feed can be fractionated into a varietyof products. One option for fractionation can be to separate thehydroprocessed feed into portions boiling above and below a desiredconversion temperature, such as 700° F. (371° C.). In this option, theportion boiling below 371° C. corresponds to a portion containingnaphtha boiling range product, diesel boiling range product,hydrocarbons lighter than a naphtha boiling range product, andcontaminant gases generated during hydroprocessing such as H₂S and NH₃.Optionally, one or more of these various product streams can beseparated out as a distinct product by the fractionation, or separationof these products from a portion boiling below 371° C. can occur in alater fractionation step. Optionally, the portion boiling below 371° C.can be fractionated to also include a kerosene product.

The portion boiling above 371° C. corresponds to a bottoms fraction.This bottoms fraction can be passed into a second hydroprocessing stagethat includes one or more types of hydroprocessing catalysts. The secondstage can include one or more beds of a hydrocracking catalyst, one ormore beds of a dewaxing catalyst, and optionally one or more beds of ahydrofinishing or aromatic saturation catalyst. The reaction conditionsfor hydroprocessing in the second stage can be the same as or differentfrom the conditions used in the first stage. Because of thehydrotreatment processes in the first stage and the fractionation, thesulfur content of the bottoms fraction, on a combined gas and liquidsulfur basis, can be 1000 wppm or less, or about 500 wppm or less, orabout 100 wppm or less, or about 50 wppm or less, or about 10 wppm orless.

Still another option can be to include one or more beds ofhydrofinishing or aromatic saturation catalyst in a separate third stageand/or reactor. In the discussion below, a reference to hydrofinishingis understood to refer to either hydrofinishing or aromatic saturation,or to having separate hydrofinishing and aromatic saturation processes.In situations where a hydrofinishing process is desirable for reducingthe amount of aromatics in a feed, it can be desirable to operate thehydrofinishing process at a temperature that is colder than thetemperature in the prior hydroprocessing stages. For example, it may bedesirable to operate a dewaxing process at a temperature above 300° C.while operating a hydrofinishing process at a temperature below 280° C.One way to facilitate having a temperature difference between a dewaxingand/or hydrocracking process and a subsequent hydrofinishing process isto house the catalyst beds in separate reactors. A hydrofinishing oraromatic saturation process can be included either before or afterfractionation of a hydroprocessed feed.

FIG. 1 shows an example of a general reaction system that utilizes tworeaction stages suitable for use in various embodiments of theinvention. In FIG. 1, a reaction system is shown that includes a firstreaction stage 110, a separation stage 120, and a second reaction stage130. Both the first reaction stage 110 and second reaction stage 130 arerepresented in FIG. 1 as single reactors. Alternatively, any convenientnumber of reactors can be used for the first stage 110 and/or the secondstage 130. The separation stage 120 is a stage capable of separating adiesel fuel product from the effluent generated by the first stage.

A suitable feedstock 115 is introduced into first reaction stage 110along with a hydrogen-containing stream 117. The feedstock ishydroprocessed in the presence of one or more catalyst beds undereffective conditions. The effluent 119 from first reaction stage 110 ispassed into separation stage 120. The separation stage 120 can produceat least a diesel product fraction 124, a bottoms fraction 126, and gasphase fraction 128. The gas phase fraction can include both contaminantssuch as H₂S or NH₃ as well as low boiling point species such as C₁-C₄hydrocarbons. Optionally, the separation stage 120 can also produce anaphtha fraction 122 and/or a kerosene fraction (not shown). The bottomsfraction 126 from the separation stage is used as input to the secondhydroprocessing stage 130, along with a second hydrogen stream 137. Thebottoms fraction is hydroprocessed in second stage 130. At least aportion of the effluent from second stage 130 can be sent to afractionator 140 for production of one or more products, such as asecond naphtha product 142, a second diesel product 144, or a lubricantbase oil product 146. Another portion of the bottoms from thefractionator 140 can optionally be recycled back 147 to second stage130.

FIG. 7 shows an example of a general reaction system that utilizes threereaction stages suitable for use in alternative embodiments of theinvention. In FIG. 7, a reaction system is shown that includes a firstreaction stage 210, a first fractionation stage 220, a second reactionstage 230, a second fractionation stage 240, and a third reaction stage250. The first reaction stage 210, second reaction stage 230 and thirdreaction stage 250 are represented in FIG. 7 as single reactors.Alternatively, any convenient number of reactors can be used for thefirst stage 210, second stage 230 and/or third stage 250. A suitablefeedstock 215 is introduced into first reaction stage 210 along with ahydrogen-containing stream 217. The feedstock is hydroprocessed in thepresence of one or more catalyst beds under effective conditions. In oneform, the first reaction stage 210 may be a conventional hydrotreatingreactor operating at effective hydrotreating conditions. The firstreaction stage effluent 219 is fed to a first fractionator 220. Thefirst fractionator 220 is a stage capable of removing a firstfuel/diesel range material 228 and a first lube range material 226. Thefirst lube range material 226 from the fractionator is used as input tothe second reaction stage/hydroprocessing stage 230 along with a secondhydrogen stream 237. The first lube range material 226 is hydroprocessedin the second reaction stage 230. In one form, the second reaction stage230 may be a hydrodewaxing reactor loaded with a dewaxing catalyst andoperated under effective dewaxing conditions. The second effluent 239from the second reaction stage 230 is passed into a second fractionator240. The second fractionator 240 can produce a second fuel/diesel rangematerial 238 and a second lube range material 236. The second lube rangematerial 236 from the second fractionator may be used as input to thethird reaction stage/hydroprocessing stage 250, along with a thirdhydrogen stream 247. The second lube range material 236 ishydroprocessed in the third reaction stage 250. In one form, the thirdreaction stage 230 may be a hydrocracking reactor loaded with ahydrocracking catalyst. At least a portion of the effluent 259 fromthird reaction stage 250 can then be sent to a fractionator (not shown)for production of one or more products, such as a naphtha product 242, afuel/diesel product 244, or a lubricant base oil product 246. Anotherportion of the bottoms 261 from the third reaction stage 250 canoptionally be recycled back to either the second reaction stage 230 viarecycle stream 263 or the second fractionation stage 240 via recyclestream 265 or a combination thereof. Recycle stream 263 is utilized whenthe product from third reaction stage 250 does not meet cold flowproperty specifications of the diesel product 244 or lubricant base oilproduct 246 and further dewaxing is necessary to meet thespecifications. Recycle stream 265 is utilized when the product fromthird reaction stage 250 does not need further dewaxing to meet the coldflow property specifications of the diesel product 244 or lubricant baseoil product 246. In another form, the process configuration of FIG. 7may further include a hydrofinishing reactor after the third reactionstage and prior to the fractionator. The hydrofinishing reactor may beloading with a hydrofinishing catalyst and run at effective reactionconditions.

The process configuration of FIG. 7 maximizes the fuel/diesel yield in a3-stage hydrocracker. The configuration produces a diesel productpossessing superior cold flow properties. In contrast with the currentstate of the art, the diesel product coming from a hydrocracker may notproduce diesel with ideal cold flow properties and would have to besubsequently dewaxed to improve product quality. With the processconfiguration of FIG. 7, all the diesel product would be sufficientlydewaxed before exiting the system to meet cold flow propertyrequirements.

FIG. 8 shows an example of a general reaction system that utilizes fourreaction stages suitable for use in alternative embodiments of theinvention. In FIG. 8, a reaction system is shown that includes a firstreaction stage 310, a first fractionation stage 320, a second reactionstage 330, a second fractionation stage 340, a third reaction stage 350,and an optional fourth reaction stage 360. The first reaction stage 310,second reaction stage 330, a third reaction stage 350 and a fourthreaction stage 360 are represented in FIG. 8 as single reactors.Alternatively, any convenient number of reactors can be used for thefirst stage 310, second stage 330, third stage 350 and/or fourth stage360. A suitable feedstock 315 is introduced into first reaction stage310 along with a hydrogen-containing stream 317. Hydrogen-containingstreams may also be introduced into the second reaction stage 330, thirdreaction stage 350 and fourth reaction stage 360 as streams 337, 347 and357, respectively. The first reaction stage 310 is a hydrotreatingreactor operating under effective hydrotreating conditions, but may alsoinclude optionally stacked beds with hydroisomerization and/orhydrocracking catalysts. The first reaction stage effluent 319 is fed toa first fractionator 320. The first fractionator 320 is a stage capableof removing a first fuel/diesel range material 328 and a first luberange material 326. In the second reaction stage 330, the first luberange material 326 is hydrocracked to raise the VI by cracking ofnaphthenes under effective hydrocracking conditions. This secondreaction stage 330 serves as the primary hydrocracker for the bottoms326 from first fractionator 320. Optionally, there may also be withinthe second reaction stage 330 a stacked configuration utilizing adewaxing catalyst above or below the hydrocracking catalyst. For maximumlube generation, the hydrocracking catalyst would be located prior tothe dewaxing catalyst in the second reaction stage 330. The secondreaction stage effluent 339 is fed to a second fractionator 340. Thesecond fractionator 340 separates a second fuel/diesel range material338 from the second lube range material 336 exiting the second reactionstage 330. The second fuel/diesel range material 338 is then combinedwith the first fuel/diesel range material 328 to form a combinedfuel/diesel range material 351, which may be optionally passed to thefourth reaction stage 360, which is typically a hydrofinishing reactoroperating at effective hydrofinishing conditions or a hydrodewaxingreactor operating at effective dewaxing conditions. The fourth reactionstage 360 serves as a isomerization reactor to improve the cold flowproperties of at least one of the first lube range material 326 andsecond fuel/diesel range material 338 or the combined fuel/diesel rangematerial 351. Alternatively, either the second fuel/diesel rangematerial 338, or the combined fuel/diesel range material 351 may bypassthe fourth reaction stage 360 where no cold flow improvement is needed.In the third reaction stage 350, the reactor is used to improve theperformance of the second lube range material 336. The third reactionstage 350 may include a dewaxing catalyst, an aromatic saturationcatalyst or both and operates to improve the cold flow properties. Thethird reaction stage effluent 343 results in a third lube range material343.

In FIG. 8, flow path 342 will be chosen if the second lube rangematerial 336 from second fractionator 340 does not require improved lubeperformance through aromatic saturation and/or dewaxing by bypassing thethird reaction stage 350. This configuration eliminates the thirdreaction stage 350. Flow path 341 will be chosen if the second luberange material 336 from second fractionator 340 does require improvedlube performance through aromatic saturation and/or dewaxing by passingthrough the third reaction stage 350. Flow path 352 will be chosen ifthe combined fuel/diesel range material 351 from the first and secondfractionators need improved cold flow properties through dewaxingthrough the fourth reaction stage 360. Finally, flow path 353 will bechosen if the combined fuel/diesel range material 351 from the first andsecond fractionators do not need improved cold flow properties throughdewaxing through the fourth reaction stage 360. This configurationeliminates the fourth reaction stage 360.

FIG. 9 shows an example of a general reaction system that utilizes threereaction stages suitable for use in alternative embodiments of theinvention. In FIG. 9, a reaction system is shown that includes a firstreaction stage 410, a first fractionation stage 420, a second reactionstage 430, a third reaction stage 440, and a second fractionation stage450. The first reaction stage 410, second reaction stage 430 and thirdreaction stage 440 are represented in FIG. 9 as single reactors.Alternatively, any convenient number of reactors can be used for thefirst stage 410, second stage 430 and/or third stage 440. A suitablefeedstock 415 is introduced into first reaction stage 410 along with ahydrogen-containing stream 417. The feedstock is hydroprocessed in thepresence of one or more catalyst beds under effective conditions. In oneform, the first reaction stage 410 may be a conventional hydrotreatingreactor operating at effective hydrotreating conditions. The firstreaction stage effluent 419 is fed to a first fractionator 420. Thefirst fractionator 420 is a stage capable of removing a firstfuel/diesel range material 428 and a first lube range material 426. Thefirst lube range material 426 from the fractionator is used as input tothe second reaction stage/hydroprocessing stage 430 along with a secondhydrogen stream 427. The first lube range material 426 is hydroprocessedin the second reaction stage 430. In one form, the second reaction stage430 may be a hydrocracking reactor loaded with a hydrocracking catalyst.The second effluent 436 from the second reaction stage 430 is passedinto a third reaction stage 440. In one form, the third reaction stage440 may be a hydrodewaxing reactor with an input hydrogen containingstream 437 loaded with a dewaxing catalyst and operating under effectivehydrodewaxing conditions. The effluent 445 from the third reaction stagemay then be input to a second fractionator 450. The second fractionator450 can produce a second fuel/diesel range material 444 and a secondlube range material 446. The second fractionator 450 may produce one ormore products, such as a naphtha and LPG product 442, a fuel/dieselproduct 444, or a lubricant base oil product 446. Optionally, at least aportion of the first fuel/diesel range material 428 from the firstfractionator 420 may be recycled to the third reaction stage 440 viaflow line 438 where an improvement in cold flow properties of thefuel/diesel product is desired. Alternatively, a portion or all of thefirst fuel/diesel range material 428 from first fractionator 420 may berecycled to the third reaction stage (see flow line 439). The first andsecond fuel/diesel range materials 439 and 444 may then be combined toform a combined fuel/diesel product 448. The reaction system of FIG. 9is particularly suitable for coproducing diesel and lube oil with goodlow temperature properties while producing limited amounts of naphthaand LPG.

FIG. 2 shows examples of four catalyst configurations (A-D) that can beemployed in a first stage under sour conditions. Configuration A shows afirst reaction stage that includes hydrotreating catalyst. ConfigurationB shows a first reaction stage that includes beds of a hydrotreatingcatalyst and a dewaxing catalyst. Configuration C shows a first reactionstage that includes beds of a hydrotreating catalyst, a hydrocrackingcatalyst, and a dewaxing catalyst. Configuration D shows a firstreaction stage that includes beds of a hydrotreating catalyst, adewaxing catalyst, and a hydrocracking. Note that the reference here to“beds” of catalyst can include embodiments where a catalyst is providedas a portion of a physical bed within a stage.

The selection of a configuration from Configurations A, B, C, or D canbe based on a desired type of product. For example, Configuration Bincludes a hydrotreatment catalyst and a dewaxing catalyst. A sourreaction stage based on Configuration B can be useful for producing aneffluent with improved cold flow properties relative to Configuration A.A diesel fuel produced from processing in Configuration B can have animproved cloud point. The yield of diesel fuel will also be improvedwhile reducing the amount of bottoms. The bottoms from Configuration Bcan also have an improved pour point. After fractionation to separateout products such as a diesel fuel product, as well as contaminant gasessuch as H₂S and NH₃, the bottoms can be further processed in a secondstage.

Configuration C can also provide a higher yield of diesel product ascompared to Configuration A, along with an improved cloud point.Additionally, based on the presence of hydrocracking catalyst,Configuration C has benefits for producing a lube product from thebottoms portion. Relative to Configuration A, the pour point of thebottoms may be higher or lower. The dewaxing process will tend to lowerthe pour point of the bottoms fraction, while a hydrocracking processmay tend to increase the pour point. Configuration D can provide agreater yield of diesel as compared to Configuration C, with acorresponding decrease in the amount of bottoms. In Configuration D, thedewaxing catalyst can increase the branching in the paraffinic moleculesin the feed, which can increase the ability for the hydrocrackingcatalyst to convert the paraffinic molecules to lower boiling pointspecies.

As an alternative, Configurations C and D can be compared to aconventional reactor containing a hydrotreating catalyst followed by ahydrocracking catalyst. Configurations C and D both can provide a dieselproduct with an improved cloud point relative to a conventionhydrotreating/hydrocracking configuration, due to the presence of thedewaxing catalyst. The pour point for the bottoms in Configurations Cand D can be lower than the bottoms for a conventionalhydrotreating/hydrocracking process.

The bottoms from processing in a stage having a configurationcorresponding to one of Configurations B, C, or D can then be processedin a second stage. Due to fractionation, the second stage can be a cleanservice stage, with a sulfur content of less than about 1000 wppm on acombined gas and liquid phase sulfur basis. FIG. 3 shows examples ofcatalyst configurations (E, F, G, and H) that can be employed in asecond stage. Configuration E shows a second reaction stage thatincludes beds of dewaxing catalyst and hydrocracking catalyst.Configuration F shows a second reaction stage that includes beds ofhydrocracking catalyst and dewaxing catalyst. Configuration G shows asecond reaction stage that includes beds of dewaxing catalyst,hydrocracking catalyst, and more dewaxing catalyst. Note that inConfiguration G, the second set of beds of dewaxing catalyst can includethe same type(s) of dewaxing catalyst as the first group of beds ordifferent type(s) of catalyst.

Optionally, a final bed of hydrofinishing catalyst could be added to anyof Configurations E, F, or G. Configuration H shows this type ofconfiguration, with beds of hydrocracking, dewaxing, and hydrofinishingcatalyst. As noted above, each stage can include one or more reactors,so one option can be to house the hydrofinishing catalyst in a separatereactor from the catalysts shown for Configurations E, F, or G. Thisseparate reactor is schematically represented in Configuration H. Notethat the hydrofinishing beds can be included either before or afterfractionation of the effluent from the second (or non-sour) reactionstage. As a result, hydrofinishing can be performed on a portion of theeffluent from the second stage if desired.

Configurations E, F, and G can be used to make both a fuel product and alubricant base oil product from the bottoms of the first sour stage. Theyield of diesel fuel product can be higher for Configuration F relativeto Configuration E, and higher still for Configuration G. Of course, therelative diesel yield of the configurations can be modified, such as byrecycling a portion of the bottoms for further conversion.

Any of Configurations B, C, or D can be matched with any ofConfigurations E, F, or G in a two stage reaction system, such as thetwo stage system shown in FIG. 1. The bottoms portion from a secondstage of any of the above combinations can have an appropriate pourpoint for use as a lubricant oil base stock, such as a Group II, GroupII+, or Group III base stock. However, the aromatics content may be toohigh depending on the nature of the feed and the selected reactionconditions. Therefore a hydrofinishing stage can optionally be used withany of the combinations.

It is noted that some combinations of Configuration B, C, or D with aconfiguration from Configuration E, F, or G will result in the final bedof the first stage being of a similar type of catalyst to the initialbed of the second stage. For example, a combination of Configuration Cwith Configuration G would result in having dewaxing catalyst in boththe last bed of the first stage and in the initial bed of the secondstage. This situation still is beneficial, as the consecutive stages canallow less severe reaction conditions to be selected in each stage whilestill achieving desired levels of improvement in cold flow properties.This is in addition to the benefit of having dewaxing catalyst in thefirst stage to improve the cold flow properties of a diesel productseparated from the effluent of the first stage.

Although Configurations B, C, and D have some advantages relative toConfiguration A, in some embodiments Configuration A can also be usedfor the first stage. In particular, Configuration A can be used withConfigurations E or G, where a dewaxing catalyst is followed by ahydrocracking catalyst.

Note that Configurations E, F, G, or H can optionally be expanded toinclude still more catalyst beds. For example, one or more additionaldewaxing and/or hydrocracking catalyst beds can be included after thefinal dewaxing or catalyst bed shown in a Configuration. Additional bedscan be included in any convenient order. For example, one possibleextension for Configuration E would be to have a series of alternatingbeds of dewaxing catalyst and hydrocracking catalyst. For a series offour beds, this could result in a series ofdewaxing—hydrocracking—dewaxing—hydrocracking. A similar extension ofConfiguration F could be used to make a series ofhydrocracking—dewaxing—hydrocracking dewaxing. A hydrofinishing catalystbed could then be added after the final additional hydrocracking ordewaxing catalyst bed.

One example of a combination of configurations can be a combination ofConfiguration B with any of Configurations E, F, G, or H, or inparticular a combination with Configuration F or H. These types ofconfigurations can potentially be advantageous for increasing the dieselyield from a feedstock while reducing the amount of naphtha andmaintaining a reasonable yield of lubricant base oil. Configuration Bdoes not include a hydrocracking stage, so any diesel boiling rangemolecules present in a feed after only hydrotreatment and dewaxing areremoved prior to hydrocracking. The second stage can then be operated togenerate a desired level of conversion to diesel boiling range moleculeswithout overcracking of any diesel molecules present in the initialfeed.

Another example of a combination of configurations can be a combinationof Configuration D with any of Configurations E, F, G, or H, or inparticular a combination with Configuration E or G. These types ofconfigurations can potentially be advantageous for maximizing the dieselyield from a feedstock. In Configuration D, the initial dewaxingcatalyst bed can be used to make longer chain paraffins in a feedstockmore accessible to the following hydrocracking catalyst. This can allowfor the higher amounts of conversion under milder conditions, as thedewaxing catalyst is used to facilitate the hydrocracking instead ofusing increased temperature or hydrogen partial pressure. The conversionprocess can be continued in the second stage. Note that this type ofconfiguration can include a recycle loop on the second stage to furtherincrease diesel production. This could include an extinction recycle ifno lube product is desired.

Yet another example of a combination of configurations can be acombination of Configuration C with any of Configurations E, F, G, or H,or in particular a combination with Configuration F or H. These types ofconfigurations can potentially be advantageous for emphasizing lubricantbase oil production in a reduced footprint reactor. Having a dewaxingcatalyst in Configuration C after the initial hydrocracking stage canallow the initial hydrocracking to occur with a reduced impact on theparaffin molecules in a feed. This can preserve a greater amount oflubricant base oil yield while still having the benefit of producing adewaxed diesel fuel product from the first reaction stage.

If a lubricant base stock product is desired, the lubricant base stockproduct can be further fractionated to form a plurality of products. Forexample, lubricant base stock products can be made corresponding to a 2cSt cut, a 4 cSt cut, a 6 cSt cut, and/or a cut having a viscosityhigher than 6 cSt. For example, a lubricant base oil product fractionhaving a viscosity of at least 2 cSt can be a fraction suitable for usein low pour point application such as transformer oils, low temperaturehydraulic oils, or automatic transmission fluid. A lubricant base oilproduct fraction having a viscosity of at least 4 cSt can be a fractionhaving a controlled volatility and low pour point, such that thefraction is suitable for engine oils made according to SAE J300 in 0 W-or 5 W- or 10 W-grades. This fractionation can be performed at the timethe diesel (or other fuel) product from the second stage is separatedfrom the lubricant base stock product, or the fractionation can occur ata later time. Any hydrofinishing and/or aromatic saturation can occureither before or after fractionation. After fractionation, a lubricantbase oil product fraction can be combined with appropriate additives foruse as an engine oil or in another lubrication service.

Hydrotreatment Conditions

Hydrotreatment is typically used to reduce the sulfur, nitrogen, andaromatic content of a feed. Hydrotreating conditions can includetemperatures of 200° C. to 450° C., or 315° C. to 425° C.; pressures of250 psig (1.8 MPa) to 5000 psig (34.6 MPa) or 300 psig (2.1 MPa) to 3000psig (20.8 MPa); Liquid Hourly Space Velocities (LHSV) of 0.2-10 h⁻¹;and hydrogen treat rates of 200 scf/B (35.6 m³/m³) to 10,000 scf/B (1781m³/m³), or 500 (89 m³/m³) to 10,000 scf/B (1781 m³/m³).

Hydrotreating catalysts are typically those containing Group VIB metals(based on the Periodic Table published by Fisher Scientific), andnon-noble Group VIII metals, i.e., iron, cobalt and nickel and mixturesthereof. These metals or mixtures of metals are typically present asoxides or sulfides on refractory metal oxide supports. Suitable metaloxide supports include low acidic oxides such as silica, alumina ortitania, preferably alumina. Preferred aluminas are porous aluminas suchas gamma or eta having average pore sizes from 50 to 200 Å, or 75 to 150Å; a surface area from 100 to 300 m²/g, or 150 to 250 m²/g; and a porevolume of from 0.25 to 1.0 cm³/g, or 0.35 to 0.8 cm³/g. The supports arepreferably not promoted with a halogen such as fluorine as thisgenerally increases the acidity of the support.

Preferred metal catalysts include cobalt/molybdenum (1-10% Co as oxide,10-40% Mo as oxide), nickel/molybdenum (1-10% Ni as oxide, 10-40% Co asoxide), or nickel/tungsten (1-10% Ni as oxide, 10-40% W as oxide) onalumina. Examples of suitable nickel/molybdenum catalysts includeKF-840, KF-848, or a stacked bed of KF-848 or KF-840 and Nebula-20.

Alternatively, the hydrotreating catalyst can be a bulk metal catalyst,or a combination of stacked beds of supported and bulk metal catalyst.By bulk metal, it is meant that the catalysts are unsupported whereinthe bulk catalyst particles comprise 30-100 wt. % of at least one GroupVIII non-noble metal and at least one Group VIB metal, based on thetotal weight of the bulk catalyst particles, calculated as metal oxidesand wherein the bulk catalyst particles have a surface area of at least10 m²/g. It is furthermore preferred that the bulk metal hydrotreatingcatalysts used herein comprise about 50 to about 100 wt %, and even morepreferably about 70 to about 100 wt %, of at least one Group VIIInon-noble metal and at least one Group VIB metal, based on the totalweight of the particles, calculated as metal oxides. The amount of GroupVIB and Group VIII non-noble metals can easily be determined VIBTEM-EDX.

Bulk catalyst compositions comprising one Group VIII non-noble metal andtwo Group VIB metals are preferred. It has been found that in this case,the bulk catalyst particles are sintering-resistant. Thus the activesurface area of the bulk catalyst particles is maintained during use.The molar ratio of Group VIB to Group VIII non-noble metals rangesgenerally from 10:1-1:10 and preferably from 3:1-1:3. In the case of acore-shell structured particle, these ratios of course apply to themetals contained in the shell. If more than one Group VIB metal iscontained in the bulk catalyst particles, the ratio of the differentGroup VIB metals is generally not critical. The same holds when morethan one Group VIII non-noble metal is applied. In the case wheremolybdenum and tungsten are present as Group VIB metals, themolybenum:tungsten ratio preferably lies in the range of 9:1-1:9.Preferably the Group VIII non-noble metal comprises nickel and/orcobalt. It is further preferred that the Group VIB metal comprises acombination of molybdenum and tungsten. Preferably, combinations ofnickel/molybdenum/tungsten and cobalt/molybdenum/tungsten andnickel/cobalt/molybdenum/tungsten are used. These types of precipitatesappear to be sinter-resistant. Thus, the active surface area of theprecipitate is maintained during use. The metals are preferably presentas oxidic compounds of the corresponding metals, or if the catalystcomposition has been sulfided, sulfidic compounds of the correspondingmetals.

It is also preferred that the bulk metal hydrotreating catalysts usedherein have a surface area of at least 50 m²/g and more preferably of atleast 100 m²/g. It is also desired that the pore size distribution ofthe bulk metal hydrotreating catalysts be approximately the same as theone of conventional hydrotreating catalysts. Bulk metal hydrotreatingcatalysts have a pore volume of 0.05-5 ml/g, or of 0.1-4 ml/g, or of0.1-3 ml/g, or of 0.1-2 ml/g determined by nitrogen adsorption.Preferably, pores smaller than 1 nm are not present. The bulk metalhydrotreating catalysts can have a median diameter of at least 50 nm, orat least 100 nm. The bulk metal hydrotreating catalysts can have amedian diameter of not more than 5000 μm, or not more than 3000 μm. Inan embodiment, the median particle diameter lies in the range of 0.1-50μm and most preferably in the range of 0.5-50 μm.

Optionally, one or more beds of hydrotreatment catalyst can be locateddownstream from a hydrocracking catalyst bed and/or a dewaxing catalystbed in the first stage. For these optional beds of hydrotreatmentcatalyst, the hydrotreatment conditions can be selected to be similar tothe conditions above, or the conditions can be selected independently.

Hydrocracking Conditions

Hydrocracking catalysts typically contain sulfided base metals or GroupVIII noble metals like Pt and/or Pd on acidic supports, such asamorphous silica alumina, cracking zeolites such as USY, or acidifiedalumina. Often these acidic supports are mixed or bound with other metaloxides such as alumina, titania or silica.

A hydrocracking process in the first stage (or otherwise under sourconditions) can be carried out at temperatures of 200° C. to 450° C.,hydrogen partial pressures of from 250 psig to 5000 psig (1.8 MPa to34.6 MPa), liquid hourly space velocities of from 0.2 h⁻¹ to 10 h⁻¹, andhydrogen treat gas rates of from 35.6 m³/m³ to 1781 m³/m³ (200 SCF/B to10,000 SCF/B). Typically, in most cases, the conditions will havetemperatures in the range of 300° C. to 450° C., hydrogen partialpressures of from 500 psig to 2000 psig (3.5 MPa-13.9 MPa), liquidhourly space velocities of from 0.3 h⁻¹ to 2 h⁻¹ and hydrogen treat gasrates of from 213 m³/m³ to 1068 m³/m³ (1200 SCF/B to 6000 SCF/B).

A hydrocracking process in a second stage (or otherwise under non-sourconditions) can be performed under conditions similar to those used fora first stage hydrocracking process, or the conditions can be different.In an embodiment, the conditions in a second stage can have less severeconditions than a hydrocracking process in a first (sour) stage. Thetemperature in the hydrocracking process can be 20° C. less than thetemperature for a hydrocracking process in the first stage, or 30° C.less, or 40° C. less. The pressure for a hydrocracking process in asecond stage can be 100 psig (690 kPa) less than a hydrocracking processin the first stage, or 200 psig (1380 kPa) less, or 300 psig (2070 kPa)less.

Hydrofinishing and/or Aromatic Saturation Process

In some embodiments, a hydrofinishing and/or aromatic saturation processcan also be provided. The hydrofinishing and/or aromatic saturation canoccur after the last hydrocracking or dewaxing stage. The hydrofinishingand/or aromatic saturation can occur either before or afterfractionation. If hydrofinishing and/or aromatic saturation occurs afterfractionation, the hydrofinishing can be performed on one or moreportions of the fractionated product, such as being performed on one ormore lubricant base stock portions. Alternatively, the entire effluentfrom the last hydrocracking or dewaxing process can be hydrofinishedand/or undergo aromatic saturation.

In some situations, a hydrofinishing process and an aromatic saturationprocess can refer to a single process performed using the same catalyst.Alternatively, one type of catalyst or catalyst system can be providedto perform aromatic saturation, while a second catalyst or catalystsystem can be used for hydrofinishing. Typically a hydrofinishing and/oraromatic saturation process will be performed in a separate reactor fromdewaxing or hydrocracking processes for practical reasons, such asfacilitating use of a lower temperature for the hydrofinishing oraromatic saturation process. However, an additional hydrofinishingreactor following a hydrocracking or dewaxing process but prior tofractionation could still be considered part of a second stage of areaction system conceptually.

Hydrofinishing and/or aromatic saturation catalysts can includecatalysts containing Group VI metals, Group VIII metals, and mixturesthereof. In an embodiment, preferred metals include at least one metalsulfide having a strong hydrogenation function. In another embodiment,the hydrofinishing catalyst can include a Group VIII noble metal, suchas Pt, Pd, or a combination thereof. The mixture of metals may also bepresent as bulk metal catalysts wherein the amount of metal is about 30wt. % or greater based on catalyst. Suitable metal oxide supportsinclude low acidic oxides such as silica, alumina, silica-aluminas ortitania, preferably alumina. The preferred hydrofinishing catalysts foraromatic saturation will comprise at least one metal having relativelystrong hydrogenation function on a porous support. Typical supportmaterials include amorphous or crystalline oxide materials such asalumina, silica, and silica-alumina. The support materials may also bemodified, such as by halogenation, or in particular fluorination. Themetal content of the catalyst is often as high as about 20 weightpercent for non-noble metals. In an embodiment, a preferredhydrofinishing catalyst can include a crystalline material belonging tothe M41S class or family of catalysts. The M41S family of catalysts aremesoporous materials having high silica content. Examples includeMCM-41, MCM-48 and MCM-50. A preferred member of this class is MCM-41.If separate catalysts are used for aromatic saturation andhydrofinishing, an aromatic saturation catalyst can be selected based onactivity and/or selectivity for aromatic saturation, while ahydrofinishing catalyst can be selected based on activity for improvingproduct specifications, such as product color and polynuclear aromaticreduction.

Hydrofinishing conditions can include temperatures from about 125° C. toabout 425° C., preferably about 180° C. to about 280° C., totalpressures from about 500 psig (3.4 MPa) to about 3000 psig (20.7 MPa),preferably about 1500 psig (10.3 MPa) to about 2500 psig (17.2 MPa), andliquid hourly space velocity from about 0.1 hr⁻¹ to about 5 hr⁻¹ LHSV,preferably about 0.5 hr⁻¹ to about 1.5 hr⁻¹.

Dewaxing Process

In various embodiments, catalytic dewaxing can be included as part ofthe hydroprocessing in a first stage (or otherwise in a sourenvironment.) Because a separation does not occur in the first stage,any sulfur in the feed at the beginning of the stage will still be inthe effluent that is passed to the catalytic dewaxing step in some form.For example, consider a first stage that includes hydrotreatmentcatalyst, hydrocracking catalyst, and dewaxing catalyst. A portion ofthe organic sulfur in the feed to the stage will be converted to H₂Sduring hydrotreating and/or hydrocracking. Similarly, organic nitrogenin the feed will be converted to ammonia. However, without a separationstep, the H₂S and NH₃ formed during hydrotreating will travel with theeffluent to the catalytic dewaxing stage. The lack of a separation stepalso means that any light gases (C₁-C₄) formed during hydrocracking willstill be present in the effluent. The total combined sulfur from thehydrotreating process in both organic liquid form and gas phase(hydrogen sulfide) may be greater than 1,000 ppm by weight, or at least2,000 ppm by weight, or at least 5,000 ppm by weight, or at least 10,000ppm by weight, or at least 20,000 ppm by weight, or at least 40,000 ppmby weight. For the present disclosure, these sulfur levels are definedin terms of the total combined sulfur in liquid and gas forms fed to thedewaxing stage in parts per million (ppm) by weight on the hydrotreatedfeedstock basis.

Elimination of a separation step in the first reaction stage is enabledin part by the ability of a dewaxing catalyst to maintain catalyticactivity in the presence of elevated levels of nitrogen and sulfur.Conventional catalysts often require pre-treatment of a feedstream toreduce the sulfur content to less than a few hundred ppm. By contrast,hydrocarbon feedstreams containing up to 4.0 wt % of sulfur or more canbe effectively processed using the inventive catalysts. In anembodiment, the total combined sulfur content in liquid and gas forms ofthe hydrogen containing gas and hydrotreated feedstock can be at least0.1 wt %, or at least 0.2 wt %, or at least 0.4 wt %, or at least 0.5 wt%, or at least 1 wt %, or at least 2 wt %, or at least 4 wt %. Sulfurcontent may be measured by standard ASTM methods D2622.

Hydrogen treat gas circulation loops and make-up gas can be configuredand controlled in any number of ways. In the direct cascade, treat gasenters the hydrotreating reactor and can be once through or circulatedby compressor from high pressure flash drums at the back end of thehydrocracking and/or dewaxing section of the unit. In circulation mode,make-up gas can be put into the unit anywhere in the high pressurecircuit preferably into the hydrocracking/dewaxing reactor zone. Incirculation mode, the treat gas may be scrubbed with amine, or any othersuitable solution, to remove H₂S and NH₃. In another form, the treat gascan be recycled without cleaning or scrubbing. Alternately, the liquideffluent may be combined with any hydrogen containing gas, including butnot limited to H₂S containing gas.

Preferably, the dewaxing catalysts according to the invention arezeolites that perform dewaxing primarily by isomerizing a hydrocarbonfeedstock. More preferably, the catalysts are zeolites with aunidimensional pore structure. Suitable catalysts include 10-member ringpore zeolites, such as EU-1, ZSM-35 (or ferrierite), ZSM-11, ZSM-57,NU-87, SAPO-11, and ZSM-22. Preferred materials are EU-2, EU-11, ZBM-30,ZSM-48, or ZSM-23. ZSM-48 is most preferred. Note that a zeolite havingthe ZSM-23 structure with a silica to alumina ratio of from about 20:1to about 40:1 can sometimes be referred to as SSZ-32. Other molecularsieves that are isostructural with the above materials include Theta-1,NU-10, EU-13, KZ-1, and NU-23.

In various embodiments, the catalysts according to the invention furtherinclude a metal hydrogenation component. The metal hydrogenationcomponent is typically a Group VI and/or a Group VIII metal. Preferably,the metal hydrogenation component is a Group VIII noble metal.Preferably, the metal hydrogenation component is Pt, Pd, or a mixturethereof. In an alternative preferred embodiment, the metal hydrogenationcomponent can be a combination of a non-noble Group VIII metal with aGroup VI metal. Suitable combinations can include Ni, Co, or Fe with Moor W, preferably Ni with Mo or W.

The metal hydrogenation component may be added to the catalyst in anyconvenient manner. One technique for adding the metal hydrogenationcomponent is by incipient wetness. For example, after combining azeolite and a binder, the combined zeolite and binder can be extrudedinto catalyst particles. These catalyst particles can then be exposed toa solution containing a suitable metal precursor. Alternatively, metalcan be added to the catalyst by ion exchange, where a metal precursor isadded to a mixture of zeolite (or zeolite and binder) prior toextrusion.

The amount of metal in the catalyst can be at least 0.1 wt % based oncatalyst, or at least 0.15 wt %, or at least 0.2 wt %, or at least 0.25wt %, or at least 0.3 wt %, or at least 0.5 wt % based on catalyst. Theamount of metal in the catalyst can be 20 wt % or less based oncatalyst, or 10 wt % or less, or 5 wt % or less, or 2.5 wt % or less, or1 wt % or less. For embodiments where the metal is Pt, Pd, another GroupVIII noble metal, or a combination thereof, the amount of metal can befrom 0.1 to 5 wt %, preferably from 0.1 to 2 wt %, or 0.25 to 1.8 wt %,or 0.4 to 1.5 wt %. For embodiments where the metal is a combination ofa non-noble Group VIII metal with a Group VI metal, the combined amountof metal can be from 0.5 wt % to 20 wt %, or 1 wt % to 15 wt %, or 2.5wt % to 10 wt %.

Preferably, the dewaxing catalysts used in processes according to theinvention are catalysts with a low ratio of silica to alumina. Forexample, for ZSM-48, the ratio of silica to alumina in the zeolite canbe less than 200:1, or less than 110:1, or less than 100:1, or less than90:1, or less than 80:1. In various embodiments, the ratio of silica toalumina can be from 30:1 to 200:1, 60:1 to 110:1, or 70:1 to 100:1.

The dewaxing catalysts useful in processes according to the inventioncan also include a binder. In some embodiments, the dewaxing catalystsused in process according to the invention are formulated using a lowsurface area binder, a low surface area binder represents a binder witha surface area of 100 m²/g or less, or 80 m²/g or less, or 70 m²/g orless.

Alternatively, the binder and the zeolite particle size are selected toprovide a catalyst with a desired ratio of micropore surface area tototal surface area. In dewaxing catalysts used according to theinvention, the micropore surface area corresponds to surface area fromthe unidimensional pores of zeolites in the dewaxing catalyst. The totalsurface corresponds to the micropore surface area plus the externalsurface area. Any binder used in the catalyst will not contribute to themicropore surface area and will not significantly increase the totalsurface area of the catalyst. The external surface area represents thebalance of the surface area of the total catalyst minus the microporesurface area. Both the binder and zeolite can contribute to the value ofthe external surface area. Preferably, the ratio of micropore surfacearea to total surface area for a dewaxing catalyst will be equal to orgreater than 25%.

A zeolite can be combined with binder in any convenient manner. Forexample, a bound catalyst can be produced by starting with powders ofboth the zeolite and binder, combining and mulling the powders withadded water to form a mixture, and then extruding the mixture to producea bound catalyst of a desired size. Extrusion aids can also be used tomodify the extrusion flow properties of the zeolite and binder mixture.The amount of framework alumina in the catalyst may range from 0.1 to3.33 wt %, or 0.1 to 2.7 wt %, or 0.2 to 2 wt %, or 0.3 to 1 wt %.

In yet another embodiment, a binder composed of two or more metal oxidescan also be used. In such an embodiment, the weight percentage of thelow surface area binder is preferably greater than the weight percentageof the higher surface area binder.

Alternatively, if both metal oxides used for forming a mixed metal oxidebinder have a sufficiently low surface area, the proportions of eachmetal oxide in the binder are less important. When two or more metaloxides are used to form a binder, the two metal oxides can beincorporated into the catalyst by any convenient method. For example,one binder can be mixed with the zeolite during formation of the zeolitepowder, such as during spray drying. The spray dried zeolite/binderpowder can then be mixed with the second metal oxide binder prior toextrusion.

In yet another embodiment, the dewaxing catalyst is self-bound and doesnot contain a binder.

Process conditions in a catalytic dewaxing zone in a sour environmentcan include a temperature of from 200 to 450° C., preferably 270 to 400°C., a hydrogen partial pressure of from 1.8 to 34.6 mPa (250 to 5000psi), preferably 4.8 to 20.8 mPa, a liquid hourly space velocity of from0.2 to 10 v/v/hr, preferably 0.5 to 3.0, and a hydrogen circulation rateof from 35.6 to 1781 m³/m³ (200 to 10,000 scf/B), preferably 178 to890.6 m³/m³ (1000 to 5000 scf/B).

For dewaxing in the second stage (or other non-sour environment), thedewaxing catalyst conditions can be similar to those for a sourenvironment. In an embodiment, the conditions in a second stage can haveless severe conditions than a dewaxing process in a first (sour) stage.The temperature in the dewaxing process can be 20° C. less than thetemperature for a dewaxing process in the first stage, or 30° C. less,or 40° C. less. The pressure for a dewaxing process in a second stagecan be 100 psig (690 kPa) less than a dewaxing process in the firststage, or 200 psig (1380 kPa) less, or 300 psig (2070 kPa) less.

Dewaxing Catalyst Synthesis

In one form the of the present disclosure, the catalytic dewaxingcatalyst includes from 0.1 wt % to 3.33 wt % framework alumina, 0.1 wt %to 5 wt % Pt, 200:1 to 30:1 SiO₂:Al₂O₃ ratio and at least one lowsurface area, refractory metal oxide binder with a surface area of 100m²/g or less.

One example of a molecular sieve suitable for use in the claimedinvention is ZSM-48 with a SiO₂:Al₂O₃ ratio of less than 110, preferablyfrom about 70 to about 110. In the embodiments below, ZSM-48 crystalswill be described variously in terms of “as-synthesized” crystals thatstill contain the (200:1 or less SiO₂:Al₂O₃ ratio) organic template;calcined crystals, such as Na-form ZSM-48 crystals; or calcined andion-exchanged crystals, such as H-form ZSM-48 crystals.

The ZSM-48 crystals after removal of the structural directing agent havea particular morphology and a molar composition according to the generalformula:(n)SiO₂:Al₂O₃where n is from 70 to 110, preferably 80 to 100, more preferably 85 to95. In another embodiment, n is at least 70, or at least 80, or at least85. In yet another embodiment, n is 110 or less, or 100 or less, or 95or less. In still other embodiments, Si may be replaced by Ge and Al maybe replaced by Ga, B, Fe, Ti, V, and Zr.

The as-synthesized form of ZSM-48 crystals is prepared from a mixturehaving silica, alumina, base and hexamethonium salt directing agent. Inan embodiment, the molar ratio of structural directing agent:silica inthe mixture is less than 0.05, or less than 0.025, or less than 0.022.In another embodiment, the molar ratio of structural directingagent:silica in the mixture is at least 0.01, or at least 0.015, or atleast 0.016. In still another embodiment, the molar ratio of structuraldirecting agent:silica in the mixture is from 0.015 to 0.025, preferably0.016 to 0.022. In an embodiment, the as-synthesized form of ZSM-48crystals has a silica:alumina molar ratio of 70 to 110. In still anotherembodiment, the as-synthesized form of ZSM-48 crystals has asilica:alumina molar ratio of at least 70, or at least 80, or at least85. In yet another embodiment, the as-synthesized form of ZSM-48crystals has a silica:alumina molar ratio of 110 or less, or 100 orless, or 95 or less. For any given preparation of the as-synthesizedform of ZSM-48 crystals, the molar composition will contain silica,alumina and directing agent. It should be noted that the as-synthesizedform of ZSM-48 crystals may have molar ratios slightly different fromthe molar ratios of reactants of the reaction mixture used to preparethe as-synthesized form. This result may occur due to incompleteincorporation of 100% of the reactants of the reaction mixture into thecrystals formed (from the reaction mixture).

The ZSM-48 composition is prepared from an aqueous reaction mixturecomprising silica or silicate salt, alumina or soluble aluminate salt,base and directing agent. To achieve the desired crystal morphology, thereactants in reaction mixture have the following molar ratios:

SiO₂:Al₂O₃ (preferred)=70 to 110

H₂O:SiO₂=1 to 500

OH—:SiO₂=0.1 to 0.3

OH—:SiO₂ (preferred)=0.14 to 0.18

template:SiO₂=0.01−0.05

template:SiO₂ (preferred)=0.015 to 0.025

In the above ratios, two ranges are provided for both the base:silicaratio and the structure directing agent:silica ratio. The broader rangesfor these ratios include mixtures that result in the formation of ZSM-48crystals with some quantity of Kenyaite and/or needle-like morphology.For situations where Kenyaite and/or needle-like morphology is notdesired, the preferred ranges should be used.

The silica source is preferably precipitated silica and is commerciallyavailable from Degussa. Other silica sources include powdered silicaincluding precipitated silica such as Zeosil® and silica gels, silicicacid colloidal silica such as Ludox® or dissolved silica. In thepresence of a base, these other silica sources may form silicates. Thealumina may be in the form of a soluble salt, preferably the sodium saltand is commercially available from US Aluminate. Other suitable aluminumsources include other aluminum salts such as the chloride, aluminumalcoholates or hydrated alumina such as gamma alumina, pseudobohemiteand colloidal alumina. The base used to dissolve the metal oxide can beany alkali metal hydroxide, preferably sodium or potassium hydroxide,ammonium hydroxide, diquaternary hydroxide and the like. The directingagent is a hexamethonium salt such as hexamethonium dichloride orhexamethonium hydroxide. The anion (other than chloride) could be otheranions such as hydroxide, nitrate, sulfate, other halide and the like.Hexamethonium dichloride isN,N,N,N′,N′,N′-hexamethyl-1,6-hexanediammonium dichloride.

In an embodiment, the crystals obtained from the synthesis according tothe invention have a morphology that is free of fibrous morphology.Fibrous morphology is not desired, as this crystal morphology inhibitsthe catalytic dewaxing activity of ZSM-48. In another embodiment, thecrystals obtained from the synthesis according to the invention have amorphology that contains a low percentage of needle-like morphology. Theamount of needle-like morphology present in the ZSM-48 crystals can be10% or less, or 5% or less, or 1% or less. In an alternative embodiment,the ZSM-48 crystals can be free of needle-like morphology. Low amountsof needle-like crystals are preferred for some applications asneedle-like crystals are believed to reduce the activity of ZSM-48 forsome types of reactions. To obtain a desired morphology in high purity,the ratios of silica:alumina, base:silica and directing agent:silica inthe reaction mixture according to embodiments of the invention should beemployed. Additionally, if a composition free of Kenyaite and/or free ofneedle-like morphology is desired, the preferred ranges should be used.

The as-synthesized ZSM-48 crystals should be at least partially driedprior to use or further treatment. Drying may be accomplished by heatingat temperatures of from 100 to 400° C., preferably from 100 to 250° C.Pressures may be atmospheric or subatmospheric. If drying is performedunder partial vacuum conditions, the temperatures may be lower thanthose at atmospheric pressures.

Catalysts are typically bound with a binder or matrix material prior touse. Binders are resistant to temperatures of the use desired and areattrition resistant. Binders may be catalytically active or inactive andinclude other zeolites, other inorganic materials such as clays andmetal oxides such as alumina, silica, titania, zirconia, andsilica-alumina. Clays may be kaolin, bentonite and montmorillonite andare commercially available. They may be blended with other materialssuch as silicates. Other porous matrix materials in addition tosilica-aluminas include other binary materials such as silica-magnesia,silica-thoria, silica-zirconia, silica-beryllia and silica-titania aswell as ternary materials such as silica-alumina-magnesia,silica-alumina-thoria and silica-alumina-zirconia. The matrix can be inthe form of a co-gel. The bound ZSM-48 framework alumina will range from0.1 wt % to 3.33 wt % framework alumina.

ZSM-48 crystals as part of a catalyst may also be used with a metalhydrogenation component. Metal hydrogenation components may be fromGroups 6-12 of the Periodic Table based on the IUPAC system havingGroups 1-18, preferably Groups 6 and 8-10. Examples of such metalsinclude Ni, Mo, Co, W, Mn, Cu, Zn, Ru, Pt or Pd, preferably Pt or Pd.Mixtures of hydrogenation metals may also be used such as Co/Mo, Ni/Mo,Ni/W and Pt/Pd, preferably Pt/Pd. The amount of hydrogenation metal ormetals may range from 0.1 to 5 wt %, based on catalyst. In anembodiment, the amount of metal or metals is at least 0.1 wt %, or atleast 0.25 wt %, or at least 0.5 wt %, or at least 0.6 wt %, or at least0.75 wt %, or at least 0.9 wt %. In another embodiment, the amount ofmetal or metals is 5 wt % or less, or 4 wt % or less, or 3 wt % or less,or 2 wt % or less, or 1 wt % or less. Methods of loading metal ontoZSM-48 catalyst are well known and include, for example, impregnation ofZSM-48 catalyst with a metal salt of the hydrogenation component andheating. The ZSM-48 catalyst containing hydrogenation metal may also besulfided prior to use.

High purity ZSM-48 crystals made according to the above embodiments havea relatively low silica:alumina ratio. The silica:alumina ratio can be110 or less, or 90 or less, or 75 or less. This lower silica:aluminaratio means that the present catalysts are more acidic. In spite of thisincreased acidity, they have superior activity and selectivity as wellas excellent yields. They also have environmental benefits from thestandpoint of health effects from crystal form and the small crystalsize is also beneficial to catalyst activity.

For catalysts according to the invention that incorporate ZSM-23, anysuitable method for producing ZSM-23 with a low SiO₂:Al₂O₃ ratio may beused. U.S. Pat. No. 5,332,566 provides an example of a synthesis methodsuitable for producing ZSM-23 with a low ratio of SiO₂:Al₂O₃. Forexample, a directing agent suitable for preparing ZSM-23 can be formedby methylating iminobispropylamine with an excess of iodomethane. Themethylation is achieved by adding the iodomethane dropwise toiminobispropylamine which is solvated in absolute ethanol. The mixtureis heated to a reflux temperature of 77° C. for 18 hours. The resultingsolid product is filtered and washed with absolute ethanol.

The directing agent produced by the above method can then be mixed withcolloidal silica sol (30% SiO₂), a source of alumina, a source of alkalications (such as Na or K), and deionized water to form a hydrogel. Thealumina source can be any convenient source, such as alumina sulfate orsodium aluminate. The solution is then heated to a crystallizationtemperature, such as 170° C., and the resulting ZSM-23 crystals aredried. The ZSM-23 crystals can then be combined with a low surface areabinder to form a catalyst according to the invention.

The following are examples of the present disclosure and are not to beconstrued as limiting.

EXAMPLES Example 1A Synthesis of ZSM-48 Crystals with SiO₂/Al₂/O₃ Ratioof ˜70/1 and Preferred Morphology

A mixture was prepared from a mixture of DI water, HexamethoniumChloride (56% solution), Ultrasil silica, Sodium Aluminate solution(45%), and 50% sodium hydroxide solution, and ˜0.15% (to reactionmixture) of ZSM-48 seed crystals. The mixture had the following molarcomposition:

SiO2/SiO₂/Al₂O₃˜80

H₂O/SiO₂˜15

OH⁻/SiO₂˜0.15

Na⁺/SiO₂˜0.15

Template/SiO₂˜0.02

The mixture was reacted at 320° F. (160° C.) in a 5-gal autoclave withstirring at 250 RPM for 48 hours. The product was filtered, washed withdeionized (DI) water and dried at 250° F. (120° C.). The XRD pattern ofthe as-synthesized material showed the typical pure phase of ZSM-48topology. The SEM of the as-synthesized material shows that the materialwas composed of agglomerates of small irregularly shaped crystals (withan average crystal size of about 0.05 microns). The resulting ZSM-48crystals had a SiO₂/Al₂O₃ molar ratio of ˜71. The as-synthesizedcrystals were converted into the hydrogen form by three ion exchangeswith ammonium nitrate solution at room temperature, followed by dryingat 250° F. (120° C.) and calcination at 1000° F. (540° C.) for 4 hours.The resulting ZSM-48 (70:1 SiO₂:Al₂O₃) crystals had a total surface areaof ˜290 m²/g (external surface area of ˜130 m²/g), and an Alpha value of˜100, ˜40% higher than current ZSM-48(90:1 SiO₂:Al₂O₃) Alumina crystals.The H-form crystals were then steamed at 700° F., 750° F., 800° F., 900°F., and 1000° F. for 4 hours for activity enhancement and Alpha valuesof these treated products are shown below:

170 (700° F.), 150 (750° F.), 140 (800° F.), 97 (900° F.), and 25 (1000°F.).

Example 1B Preparation of the Sour Service Dewaxing Catalyst

The sour service hydroisomerization catalyst was prepared by mixing 65wt % ZSM-48 (˜70/1 SiO₂/Al₂O₃, see Example 1A) with 35 wt % P25 TiO₂binder and extruding into a 1/20″ quadralobe. This catalyst was thenprecalcined in nitrogen at 1000° F., ammonium exchanged with ammoniumnitrate, and calcined at 1000° F. in full air. The extrudate was thensteamed for 3 hours at 750° F. in full steam. The steamed catalyst wasimpregnated to 0.6 wt % platinum via incipient wetness using platinumtetraamine nitrate, dried, and then calcined at 680° F. for 3 hours inair. The ratio of micropore surface area to total surface area is about45%.

Examples below demonstrate the advantages of various portions of areaction system according to an embodiment of the invention. In variousembodiments, a dewaxing or hydroisomerization step can be included inboth a first, sour reaction stage and a second, non-sour reaction stage.

A medium vacuum gas oil feed (MVGO) was used in all examples below. Theinitial feed properties are shown in Table 1.

TABLE 1 MVGO Feed Properties MVGO Feed Properties Feed 700° F.+ in Feed(wt %) 90 Feed Pour Point, ° C. 30 Solvent Dewaxed Oil Feed Pour Point,° C. −19 Solvent Dewaxed Oil Feed 100° C. Viscosity, cSt 7.55 SolventDewaxed Oil Feed VI 57.8 Organic Sulfur in Feed (ppm by weight) 25,800Organic Nitrogen in Feed (ppm by weight) 809

Example 2 Example of Advantage of Interstage Distillate Recovery

The following example is based on process simulations using a kineticmodel. In the simulations, a feedstock is represented as a one or moregroups of molecular. The groups of molecules are based on the carbonnumber of the molecules and the molecular class of the molecules. Basedon the process conditions selected for the simulation (such as pressure,temperature, hydrogen treat gas rate, and/or space velocity), each groupof molecules is reacted according to a reaction order and rateappropriate for the group. Suitable reaction rate data for differenttypes or groups of molecules can be obtained from the publishedliterature, or reaction rate data can be generated experimentally. Theproducts of the reaction calculations for each group of molecules areused to determine an output product in the simulation. In the reactioncalculations, aromatics equilibrium can also be considered and used tomodify the calculated aromatics content in the product.

The kinetic model was used to investigate the impact of interstageseparation on diesel product yield. A pair of similar two stageconfigurations were modeled. One configuration did not have interstageseparation between the two stages. A simulated fractionation wasperformed on the effluent from the second stage to determine the yieldof various products. The second configuration included a separator toseparate the effluent from the first stage into 700° F.− and 700° F.+portions. The 700° F.+ portion was then processed in a second stage. Insimulation of the second configuration, the 700° F.− portion and theeffluent from the second stage were fractionated into diesel and lubeoil products in a common fractionator. Note that the configurationincluding interstage separation is similar to the configuration shown inFIG. 1, with the exception that FIG. 1 does not show a fraction fromseparator 120 being passed into separator 140.

In a first series of simulations, the configuration without interstageseparation was modeled. The 700° F.+ conversion for the first stage wasset at 13%, while the total conversion from the two stages was varied todetermine the yield of 400° F.-700° F. diesel product. This correspondsto a configuration including hydrocracking capability in both the firstand second stage. The results from this series of simulations are shownin FIG. 4. In the first series of simulations, a maximum diesel yield of38 vol % was predicted at 56% conversion.

In a second and third series of simulations, the configuration includinginterstage separation (similar to FIG. 1) was used. In the secondseries, the conversion in the first stage was set to 13%. In the thirdseries, the conversion in the first stage was set to 24%. As shown inFIG. 4, the maximum diesel yield in both the second series (46 vol %)and third series (49 vol %) of simulations was higher than the maximumyield in the first series without interstage separation. This increasein diesel yield was due at least in part to the removal of the 700° F.−portion of the feed between the first and second stages. The removal ofthe 700° F.− portion prevented overcracking of diesel molecules intonaphtha or other lower value products.

Example 3 Example of Improved Diesel Yield Followed by InterstageSeparation

FIG. 5 shows results from a series of runs performed on an MVGO feedusing various configurations of catalysts. For the runs in FIG. 5, afirst reactor was used that included a conventional hydrotreatingcatalyst. An MVGO feed was hydrotreated to produce a hydrotreatedeffluent having a sulfur content of less than 100 wppm. The hydrotreatedeffluent was then fractionated to remove all distillate and lighterhydrocarbons. The unconverted bottoms was hydroprocessed in a secondreactor. The second reactor included a bed of hydrocracking catalyst,and an optional bed of dewaxing catalyst either prior to or after thehydrocracking catalyst bed. The hydrocracking catalyst was HSZ-390, aUSY zeolite based catalyst. The dewaxing catalyst was selected from oneof three choices. One type of catalyst was based on a 70:1 silica toalumina ratio ZSM-48 molecular sieve bound with a P25 (DeGussa) titaniabinder. The catalyst included a 65:35 ratio of molecular sieve tobinder. The catalyst also included 2 wt % of Pt relative to the totalweight of the catalyst. Another catalyst was based on a 90:1 silica toalumina ratio ZSM-48 molecular sieve, including a DT-51D (Rhone-Poulenc)titania binder and 2 wt % of Pt. A third catalyst was based on a 64:1silica to alumina ratio ZSM-23 molecular sieve, including a Versal-300alumina binder and 2 wt % of Pt. In the discussion below, the ZSM-48 andZSM-23 catalysts may be referred to as dewaxing catalysts.

As shown in FIG. 5, eight different configurations were tested. In oneconfiguration, only the USY catalyst was included in the second reactor.In the other configurations, the USY catalyst was stacked with one ofthe other catalysts. In the configurations involving both a USY catalystand a ZSM-48 or ZSM-23 catalyst, a 70:30 ratio of USY to the othercatalyst was used. The USY catalyst could be either first or second inthe reactor in terms of contact with the feed, as shown in FIG. 5. Inthe final run shown in FIG. 5, the USY and ZSM-48 catalyst beds weresplit so that the hydrotreated feed was exposed to a 4 part series ofcatalysts (USY:ZSM-48:USY:ZSM-48). The feed was processed at a spacevelocity of 2 hr⁻¹, a pressure of 1275 psig (8.8 MPa), and a hydrogentreat gas rate of 4000 scf/bbl (7100 m³/m³). The temperature was variedfrom 320° C. to 360° C., as shown in FIG. 5.

FIG. 5 shows the yield of diesel fuel product and the 700° F.+conversion of the feed for the various runs. For the purposes of thisexample, a boiling range of 400° F.-700° F. was selected ascorresponding to a diesel fuel product. The data in FIG. 5 can be usedto compare the diesel yield, as a function of 700° F.+ conversion, for aUSY catalyst alone versus stacked beds of both USY and another catalyst.In FIG. 5, a configuration involving USY catalyst alone provided acomparable or better diesel yield as compared to configurations whereUSY catalyst was stacked above a dewaxing catalyst. One exception is fora stacked bed of the USY above 70:1 ZSM-48, where an increase in dieselyield was observed at a processing temperature of 350° C. By contrast, astacked bed having a ZSM-48 dewaxing catalyst followed by the USYcatalyst showed an improved diesel yield relative to only the USYcatalyst at a range of processing temperatures. From 330° C. to 350° C.,using either the 70:1 or the 90:1 ZSM-48 above a USY catalyst resultedin an improved diesel yield at a comparable level of conversion.

It is noted that part of the improvement in diesel yield may be due toan increase in the amount of conversion at a given temperature. However,it also appears that the maximum possible diesel yield as a function ofconversion is improved. FIG. 6 shows a plot of a portion of the datafrom FIG. 5 that demonstrates the increase in the maximum diesel yield.In FIG. 6, the run corresponding to only the USY catalyst and runsincluding one bed each of ZSM-48 and USY are shown. Based on FIG. 6, itappears that an increased diesel yield can be achieved by processing afeed using a dewaxing catalyst, such as ZSM-48, followed by ahydrocracking catalyst, such as USY, to produce 65% to 90% conversion.Optionally, the amount of conversion can be selected to be 70% to 85%.

All of the runs including a dewaxing catalyst also showed an improvementvisually in the quality of the total product. For the run using only aUSY catalyst, the total liquid product was clear but included a whiteprecipitate. For the runs including a dewaxing catalyst as well, thetotal liquid product was clear, with no apparent precipitate. Thissuggests an improvement in a cold flow property (such as cloud point orpour point) for the bottoms or lube portion of the total liquid product.

Process Example

The following is a prophetic example. An MVGO feed similar to the onedescribed above can be processed in a reaction system having two stages.In the first stage, the feed is hydrotreated under effectivehydrotreating conditions. The hydrotreated effluent is then hydrocrackedunder effective hydrocracking conditions using a catalyst based onzeolite Y. The hydrotreated, hydrocracked effluent is then dewaxed inthe presence of a dewaxing catalyst suitable for use in sour service.The catalyst can include a bound ZSM-48 zeolite impregnated with lessthan 1 wt % Pt. The above processes occur without an intermediateseparation step.

The dewaxed effluent is then fractionated. The fractionation producesboth a naphtha product fraction and a diesel product fraction. Becauseof the hydrotreatment and dewaxing processes in the first stage, thediesel product from the fractionator is suitable for use in the dieselpool. The diesel product has a sulfur content of 15 wppm or less, and acloud point below −10° C. The fractionator also produces a bottomsfraction. The bottoms fraction has a pour point below the pour point ofthe initial MVGO feed.

The bottoms fraction is passed into a second reaction stage. Due to thehydrotreatment in the first stage, the sulfur content of the bottomsfraction is less than 50 wppm. In the second stage, the bottoms fractionis hydrocracked, hydrofinished, and then dewaxed. The effluent from thesecond stage is fractionated to form a naphtha product, a dieselproduct, and a lubricant base oil product. Optionally, a portion of thelubricant base oil product is recycled to increase the amount of dieselproduced in the second reaction stage.

Additional Embodiments:

In a first embodiment, a method is provided for producing a naphthafuel, a diesel fuel, and a lubricant basestock. The method includescontacting a hydrotreated feedstock with a hydrocracking catalyst underfirst effective hydrocracking conditions to produce a hydrocrackedeffluent, the hydrotreated feedstock being cascaded to the hydrocrackingcatalyst without intermediate separation; cascading the entirehydrocracked effluent, without separation, to a catalytic dewaxingstage; dewaxing the entire hydrocracked effluent under first effectivecatalytic dewaxing conditions in the presence of a dewaxing catalyst,the dewaxing catalyst includes at least one non-dealuminated,unidimensional, 10-member ring pore zeolite and at least one Group VI orGroup VIII metal or combination thereof; fractionating the dewaxedeffluent to produce at least a naphtha product fraction, a first dieselproduct fraction, and a bottoms fraction; hydrocracking the bottomsfraction under second effective hydrocracking conditions; dewaxing thebottoms fraction under second effective catalytic dewaxing conditions;and fractionating the hydrocracked, dewaxed bottoms fraction to form atleast a second diesel product fraction and a lubricant base oil productfraction.

In a second embodiment, a method according to the first embodiment isprovided, wherein the dewaxing of the bottoms fraction is performedprior to said hydrocracking of the bottoms fraction.

In a third embodiment, a method according to any of the aboveembodiments is provided, wherein the bottoms fraction is dewaxed priorto said hydrocracking of the bottoms fraction and after saidhydrocracking of the bottoms fraction.

In a fourth embodiment, a method according to the third embodiment isprovided, wherein the bottoms fraction is dewaxed after saidhydrocracking of the bottoms fraction under third effective catalyticdewaxing conditions.

In a fifth embodiment, a method according to any of the aboveembodiments is provided, wherein the hydrocracked, dewaxed bottomsfraction is hydrofinished under effective hydrofinishing conditions.

In a sixth embodiment, a method for producing a diesel fuel and alubricant basestock is provided. The method includes contacting ahydrotreated feedstock with a dewaxing catalyst under first effectivedewaxing conditions to produce a dewaxed effluent, the dewaxing catalystincludes at least one non-dealuminated, unidimensional, 10-member ringpore zeolite and at least one Group VIII metal, the combined totalsulfur in liquid and gaseous forms fed to the dewaxing stage is greaterthan 1000 ppm by weight of sulfur on the hydrotreated feedstock basis,the hydrotreated feedstock being cascaded to the dewaxing catalystwithout intermediate separation; fractionating the dewaxed effluent toproduce at least a first diesel product fraction and a bottoms fraction;hydrocracking the bottoms fraction under second effective hydrocrackingconditions; dewaxing the bottoms fraction under second effectivecatalytic dewaxing conditions; and fractionating the hydrocracked,dewaxed bottoms fraction to form at least a second diesel productfraction and a lubricant base oil product fraction.

In a seventh embodiment, a method according to the sixth embodiment isprovided, wherein dewaxing the bottoms fraction occurs prior to saidhydrocracking of the bottoms fraction.

In an eighth embodiment, a method according to the seventh embodiment isprovided, wherein the bottoms fraction is dewaxed prior to saidhydrocracking of the bottoms fraction and dewaxed after saidhydrocracking of the bottoms fraction.

In a ninth embodiment, a method according to any of the sixth througheighth embodiments is provided, further comprising contacting thedewaxed feedstock with a hydrocracking catalyst under first effectivehydrocracking conditions prior to fractionation of the dewaxed effluent.

In a tenth embodiment, a method according to any of the aboveembodiments is provided, wherein the second effective catalytic dewaxingconditions include a temperature that is at least about 20° C. lowerthan a temperature of the first effective catalytic dewaxing conditions.

In an eleventh embodiment, a method according to any of the aboveembodiments is provided, wherein a hydrogen gas introduced as part offirst effective hydrocracking conditions or as part of first effectivedewaxing conditions is chosen from a hydrotreated gas effluent, a cleanhydrogen gas, a recycle gas and combinations thereof.

In a twelfth embodiment, a method according to any of the aboveembodiments is provided, wherein the dewaxing catalyst comprises amolecular sieve having a SiO₂:Al₂O₃ ratio of 200:1 to 30:1 and comprisesfrom 0.1 wt % to 3.33 wt % framework Al₂O₃ content, the dewaxingcatalyst including from 0.1 to 5 wt % platinum.

In a thirteenth embodiment, a method according to any of the aboveembodiments is provided, wherein the molecular sieve is EU-1, ZSM-35,ZSM-11, ZSM-57, NU-87, ZSM-22, EU-2, EU-11, ZBM-30, ZSM-48, ZSM-23, or acombination thereof.

In a fourteenth embodiment, a method according to the thirteenthembodiment is provided, wherein the molecular sieve is ZSM-48, ZSM-23,or a combination thereof, and preferably is ZSM-48.

In a fifteenth embodiment, a method according to any of the aboveembodiments is provided, wherein the dewaxing catalyst comprises atleast one low surface area metal oxide, refractory binder, the binderbeing silica, alumina, titania, zirconia, or silica-alumina.

In a sixteenth embodiment, a method according to the fifteenthembodiment is provided, wherein the metal oxide, refractory binderfurther comprises a second metal oxide, refractory binder different fromthe first metal oxide, refractory binder.

In a fifteenth embodiment, a method according to the fifteenth orsixteenth embodiment is provided, wherein the dewaxing catalystcomprises a micropore surface area to total surface area ratio ofgreater than or equal to 25%, wherein the total surface area equals thesurface area of the external zeolite plus the surface area of thebinder, the surface area of the binder being 100 m²/g or less.

In an eighteenth embodiment, a method according to any of the aboveembodiments is provided, wherein the hydrocracking catalyst is a zeoliteY based catalyst.

In a nineteenth embodiment, a method according to any of the aboveembodiments is provided, wherein fractionating to form a lubricant baseoil product fraction comprises forming a plurality of lubricant base oilproducts, including a lubricant base oil product having a viscosity ofat least 2 cSt, and a lubricant base oil product having a viscosity ofat least 4 cSt suitable for use in engine oils made according to SAEJ300 in 0 W-, 5 W-, or 10 W-grades.

In a twentieth embodiment, a method according to any of the aboveembodiments is provided, wherein at least a portion of the lubricantbase oil product fraction is recycled as an input to said hydrocrackingof the bottoms fraction.

In a twenty-first embodiment, a method according to any of the aboveembodiments is provided, wherein the first diesel product fraction has ahigher cetane rating than the hydrotreated effluent, a lower cloud pointthan the hydrotreated effluent, or both a higher cetane rating and alower cloud point than the hydrotreated effluent.

In a twenty-second embodiment, a method according to any of the aboveembodiments is provided, wherein the first diesel product fraction has acloud point of less than −10° C., the second diesel product fraction hasa cloud point of less than −10° C., and the hydrotreated effluent has acloud point that is at least 5° C. higher than the first diesel productfraction cloud point or the second diesel product fraction cloud point.

In a twenty-third embodiment, a method according to any of the aboveembodiments is provided, wherein the first effective hydrocrackingconditions include a temperature of 200° C. to 450° C., a hydrogenpartial pressure of 250 psig to 5000 psig (1.8 MPa to 34.6 MPa), aliquid hourly space velocity of 0.2 h⁻¹ to 10 h⁻¹, and a hydrogen treatgas rate of 35.6 m³/m³ to 1781 m³/m³ (200 SCF/B to 10,000 SCF/B), andpreferably the first effective hydrocracking conditions include atemperature of 300° C. to 450° C., a hydrogen partial pressure of 500psig to 2000 psig (3.5 MPa-13.9 MPa), a liquid hourly space velocity of0.3 h⁻¹ to 2 h⁻¹, and a hydrogen treat gas rate of 213 m³/m³ to 1068m³/m³ (1200 SCF/B to 6000 SCF/B).

In a twenty-fourth embodiment, a method according to any of the aboveembodiments is provided, wherein the second effective hydrocrackingconditions include a temperature of 200° C. to 450° C., a hydrogenpartial pressure of 250 psig to 5000 psig (1.8 MPa to 34.6 MPa), aliquid hourly space velocity of 0.2 h⁻¹ to 10 h⁻¹, and a hydrogen treatgas rate of 35.6 m³/m³ to 1781 m³/m³ (200 SCF/B to 10,000 SCF/B), andpreferably the second effective hydrocracking conditions include atemperature of 300° C. to 450° C., a hydrogen partial pressure of 500psig to 2000 psig (3.5 MPa-13.9 MPa), a liquid hourly space velocity of0.3 h⁻¹ to 2 h⁻¹, and a hydrogen treat gas rate of 213 m³/m³ to 1068m³/m³ (1200 SCF/B to 6000 SCF/B).

In a twenty-fifth embodiment, a method according to any of the aboveembodiments is provided, wherein the first effective dewaxing conditionsinclude a temperature of from 200° C. to 450° C., preferably 270° C. to400° C., a hydrogen partial pressure of from 1.8 MPa to 34.6 MPa (250psi to 5000 psi), preferably 4.8 mPa to 20.8 mPa (700 psi to 3000 psi),a liquid hourly space velocity of from 0.2 to 10 hr⁻¹, preferably 0.5 to3.0 hr⁻¹, and a hydrogen circulation rate of from 35.6 to 1781 m³/m³(200 to 10,000 scf/B), preferably 178 to 890.6 m³/m³ (1000 to 5000scf/B).

In a twenty-sixth embodiment, a method according to any of the aboveembodiments is provided, wherein the second effective dewaxingconditions include a temperature of from 200° C. to 450° C., preferably270° C. to 400° C., a hydrogen partial pressure of from 1.8 MPa to 34.6MPa (250 psi to 5000 psi), preferably 4.8 mPa to 20.8 mPa (700 psi to3000 psi), a liquid hourly space velocity of from 0.2 to 10 hr⁻¹,preferably 0.5 to 3.0 hr⁻¹, and a hydrogen circulation rate of from 35.6to 1781 m³/m³ (200 to 10,000 scf/B), preferably 178 to 890.6 m³/m³ (1000to 5000 scf/B).

In a twenty-seventh embodiment, a method for producing a diesel fuel anda lubricant basestock is provided. The method includes contacting afeedstock with a hydrotreating catalyst under first effectivehydrotreating conditions to produce a hydrotreated effluent;fractionating the hydrotreated effluent to produce at least a firstdiesel product fraction and a bottoms fraction; dewaxing the bottomsfraction under effective catalytic dewaxing conditions, the dewaxingcatalyst includes at least one non-dealuminated, unidimensional,10-member ring pore zeolite and at least one Group VI metal, Group VIIImetal or combination thereof; hydrocracking the bottoms fraction undereffective hydrocracking conditions; and fractionating the hydrocracked,dewaxed bottoms fraction to form at least a second diesel productfraction and a lubricant base oil product fraction.

In a twenty-eighth embodiment, a method according to the twenty-seventhembodiment is provided, wherein the effective hydrocracking conditionsinclude a temperature of 200° C. to 450° C., a hydrogen partial pressureof 250 psig to 5000 psig (1.8 MPa to 34.6 MPa), a liquid hourly spacevelocity of 0.2 h⁻¹ to 10 h⁻¹, and a hydrogen treat gas rate of 35.6m³/m³ to 1781 m³/m³ (200 SCF/B to 10,000 SCF/B).

In a twenty-ninth embodiment, a method according to any of thetwenty-seventh or twenty-eighth embodiments is provided, wherein theeffective dewaxing conditions include a temperature of from 200° C. to450° C., a hydrogen partial pressure of from 1.8 MPa to 34.6 MPa (250psi to 5000 psi), a liquid hourly space velocity of from 0.2 to 10 hr⁻¹,and a hydrogen circulation rate of from 35.6 to 1781 m³/m³ (200 to10,000 scf/B).

In a thirtieth embodiment, a method according to any of thetwenty-seventh through twenty-ninth embodiments is provided, wherein thetotal conversion of the hydrocracked, dewaxed bottoms relative to thefeedstock is 65% to 90%, preferably 70% to 85%.

In a thirty-first embodiment, provided is a method for producing adiesel fuel and a lubricant basestock, including: contacting a feedstockwith a hydrotreating catalyst under effective hydrotreating conditionsto produce a hydrotreated effluent; fractionating the hydrotreatedeffluent to produce at least a first diesel product fraction and abottoms fraction; hydrocracking the bottoms fraction under effectivehydrocracking conditions; dewaxing the bottoms fraction under effectivecatalytic dewaxing conditions, the dewaxing catalyst including at leastone non-dealuminated, unidimensional, 10-member ring pore zeolite, andat least one Group VI metal, Group VIII metal or combination thereof;and fractionating the hydrocracked, dewaxed bottoms fraction to form atleast a second diesel product fraction and a lubricant base oil productfraction.

In a thirty-second embodiment, a method according to the thirty-firstembodiment is provided, wherein at least a portion of the first dieselproduct fraction is fed to the dewaxing step.

In a thirty-third embodiment, a method according to the thirty-first tothirty-second embodiments is provided further including combining thefirst diesel product fraction and the second diesel product fraction.

In a thirty-fourth embodiment, a method according to the thirty-first tothirty-third embodiments is provided further including hydrofinishingthe hydrocracked, dewaxed bottoms fraction under effectivehydrofinishing conditions prior to the second fractionating step.

In a thirty-fifth embodiment, provided is a method for producing adiesel fuel and a lubricant basestock, including: contacting a feedstockwith a hydrotreating catalyst under effective hydrotreating conditionsto produce a hydrotreated effluent; fractionating the hydrotreatedeffluent to produce at least a first diesel product fraction and a firstbottoms fraction; dewaxing the bottoms fraction under effectivecatalytic dewaxing conditions, the dewaxing catalyst including at leastone non-dealuminated, unidimensional, 10-member ring pore zeolite, andat least one Group VI metal, Group VIII metal or combination thereof;fractionating the dewaxed bottoms fraction to form at least a seconddiesel product fraction and a second bottoms fraction, hydrocracking thesecond bottoms fraction under effective hydrocracking conditions to forma third bottoms fraction, and fractionating the third bottoms fractionto form at least a naphtha product fraction, a diesel product fractionand a lubricant base oil product fraction.

In a thirty-sixth embodiment, a method according to the thirty-fifthembodiment is provided, wherein at least a portion of the third bottomsfraction is recycled back to the dewaxing step.

In a thirty-seventh embodiment, a method according to the thirty-fifthto thirty-sixth embodiments is provided, wherein at least a portion ofthe third bottoms fraction is recycled back to the second fractionatingstep.

In a thirty-eighth embodiment, a method according to the thirty-fifth tothirty-seventh embodiments is provided further including hydrofinishingthe third bottoms fraction under effective hydrofinishing conditionsprior to the third fractionating step.

In a thirty-ninth embodiment, provided is a method for producing adiesel fuel and a lubricant basestock, including: contacting a feedstockwith a hydrotreating catalyst under effective hydrotreating conditionsto produce a hydrotreated effluent; fractionating the hydrotreatedeffluent to produce at least a first diesel product fraction and a firstbottoms fraction; hydrocracking the first bottoms fraction undereffective hydrocracking conditions to form a second bottoms fraction;fractionating the second bottoms fraction to form at least a seconddiesel product fraction and a third bottoms fraction, dewaxing at leasta portion of the third bottoms fraction under effective catalyticdewaxing conditions, the dewaxing catalyst including at least onenon-dealuminated, unidimensional, 10-member ring pore zeolite, and atleast one Group VI metal, Group VIII metal or combination thereof; andfractionating the dewaxed third bottoms fraction and the non-dewaxedthird bottoms fraction to form at least a naphtha product fraction, athird diesel product fraction and a lubricant base oil product fraction.

In a fortieth embodiment, a method according to the thirty-ninthembodiment is provided, further including dewaxing a portion of thefirst diesel product fraction, the second diesel product fraction or acombination thereof under effective catalytic dewaxing conditions.

In a forty-first embodiment, a method according to the thirty-ninth tofortieth embodiments is provided, further including combining the firstdiesel product fraction, the second diesel product fraction and thethird diesel product fraction.

In a forty-second embodiment, a method according to the thirty-ninth toforty-first embodiments is provided, further including hydrofinishingthe dewaxed third bottoms fraction under effective hydrofinishingconditions prior to the third fractionating step.

In a forty-third embodiment, provided is a method for producing anaphtha fuel, a diesel fuel, and a lubricant basestock including:contacting a hydrotreated feedstock without intermediate separation witha hydrocracking catalyst under first effective hydrocracking conditionsto produce a hydrocracked effluent; catalytically dewaxing withoutintermediate separation the entire hydrocracked effluent under firsteffective catalytic dewaxing conditions in the presence of a firstdewaxing catalyst including at least one non-dealuminated,unidimensional, 10-member ring pore zeolite, and at least one Group VImetal or Group VIII metal or combination thereof to form a dewaxedeffluent, wherein the combined total sulfur in liquid and gaseous formsfed to the catalytic dewaxing step is greater than 1000 ppm by weight ofsulfur on a hydrotreated feedstock basis; fractionating the dewaxedeffluent to produce at least a naphtha product fraction, a first dieselproduct fraction, and a bottoms fraction; hydrocracking the bottomsfraction under second effective hydrocracking conditions; catalyticallydewaxing the bottoms fraction under second effective catalytic dewaxingconditions in the presence of a second dewaxing catalyst including atleast one non-dealuminated, unidimensional, 10-member ring pore zeolite,and at least one Group VI metal or Group VIII metal or combinationthereof; and fractionating the hydrocracked, dewaxed bottoms fraction toform at least a second diesel product fraction and a lubricant base oilproduct fraction.

In a forty-fourth embodiment, a method according to the forty-thirdembodiment is provided, wherein the first dewaxing catalyst, the seconddewaxing catalyst, or both the first dewaxing catalyst and the seconddewaxing catalyst include at least one low surface area metal oxide,refractory binder.

In a forty-fifth embodiment, a method according to the forty-third toforty-fourth embodiments is provided, wherein the catalytically dewaxingof the bottoms fraction occurs prior to the second hydrocracking step,after the second hydrocracking step, or both prior to and after thesecond hydrocracking step.

All patents and patent applications, test procedures (such as ASTMmethods, UL methods, and the like), and other documents cited herein arefully incorporated by reference to the extent such disclosure is notinconsistent with this invention and for all jurisdictions in which suchincorporation is permitted.

When numerical lower limits and numerical upper limits are listedherein, ranges from any lower limit to any upper limit are contemplated.While the illustrative embodiments of the invention have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by thoseskilled in the art without departing from the spirit and scope of theinvention. Accordingly, it is not intended that the scope of the claimsappended hereto be limited to the examples and descriptions set forthherein but rather that the claims be construed as encompassing all thefeatures of patentable novelty which reside in the present invention,including all features which would be treated as equivalents thereof bythose skilled in the art to which the invention pertains.

The present invention has been described above with reference tonumerous embodiments and specific examples. Many variations will suggestthemselves to those skilled in this art in light of the above detaileddescription. All such obvious variations are within the full intendedscope of the appended claims.

What is claimed is:
 1. A method for producing a diesel fuel and alubricant basestock, comprising: contacting a feedstock with ahydrotreating catalyst under effective hydrotreating conditions toproduce a hydrotreated effluent; fractionating the hydrotreated effluentto produce at least a first diesel product fraction and a bottomsfraction; hydrocracking the bottoms fraction under effectivehydrocracking conditions; dewaxing the bottoms fraction under effectivecatalytic dewaxing conditions, the dewaxing catalyst including at leastone non-dealuminated, unidimensional, 10-member ring pore zeolite, andat least one Group VI metal, Group VIII metal, or combination thereof;and fractionating the hydrocracked, dewaxed bottoms fraction to form atleast a second diesel product fraction and a lubricant base oil productfraction.
 2. The method of claim 1, wherein at least a portion of thefirst diesel product fraction is fed to the dewaxing step.
 3. The methodof claim 1, further including combining the first diesel productfraction and the second diesel product fraction.
 4. The method of claim1, wherein the effective hydrotreating conditions include a temperatureof from 200° C. to 450° C., hydrogen partial pressure of from 1.8 MPa to34.6 MPa (250 psi to 5000 psi), a liquid hourly space velocity of from0.2 to 10 hr⁻¹, and a hydrogen circulation rate of from 35.6 to 1781m³/m³ (200 to 10,000 scf/B).
 5. The method of claim 1, wherein theeffective hydrocracking conditions include a temperature of 200° C. to450° C., a hydrogen partial pressure of 250 psig to 5000 psig (1.8 MPato 34.6 MPa), a liquid hourly space velocity of 0.2 h⁻¹ to 10 h⁻¹, and ahydrogen treat gas rate of 35.6 m³/m³ to 1781 m³/m³ (200 SCF/B to 10,000SCF/B).
 6. The method of claim 1, wherein the effective dewaxingconditions include a temperature of from 200° C. to 450° C., a hydrogenpartial pressure of from 1.8 MPa to 34.6 MPa (250 psi to 5000 psi), aliquid hourly space velocity of from 0.2 to 10 hr⁻¹, and a hydrogencirculation rate of from 35.6 to 1781 m³/m³ (200 to 10,000 scf/B). 7.The method of claim 1, wherein a hydrogen gas introduced as part ofeffective hydrotreating conditions, effective dewaxing conditions, oreffective hydrocracking conditions is chosen from a hydrotreated gaseffluent, a clean hydrogen gas, a recycle gas and combinations thereof.8. The method of claim 1, wherein the dewaxing catalyst comprises amolecular sieve having a SiO₂:Al₂O₃ ratio of 200:1 to 30:1 and comprisesfrom 0.1 wt % to 3.33 wt % framework Al₂O₃ content, the dewaxingcatalyst including from 0.1 to 5 wt % platinum.
 9. The method of claim8, wherein the molecular sieve is EU-1, ZSM-35, ZSM-11, ZSM-57, NU-87,ZSM-22, EU-2, EU-11, ZBM-30, ZSM-48, ZSM-23, or a combination thereof.10. The method of claim 9, wherein the molecular sieve is ZSM-48,ZSM-23, or a combination thereof.
 11. The method of claim 1, wherein thedewaxing catalyst comprises at least one low surface area metal oxide,refractory binder, the binder being silica, alumina, titania, zirconia,or silica-alumina.
 12. The method of claim 11, wherein the metal oxide,refractory binder further comprises a second metal oxide, refractorybinder different from the first metal oxide, refractory binder.
 13. Themethod of claim 11, wherein the dewaxing catalyst comprises a microporesurface area to total surface area ratio of greater than or equal to25%, wherein the total surface area equals the surface area of theexternal zeolite plus the surface area of the binder, the surface areaof the binder being 100 m²/g or less.
 14. The method of claim 1, whereinthe hydrocracking catalyst is a zeolite Y based catalyst.
 15. The methodof claim 1 further including hydrofinishing the hydrocracked, dewaxedbottoms fraction under effective hydrofinishing conditions prior to thesecond fractionating step.
 16. The method of claim 1, whereinfractionating to form a lubricant base oil product fraction comprisesforming a plurality of lubricant base oil products, including alubricant base oil product having a viscosity of at least 2cSt, and alubricant base oil product having a viscosity of at least 4 cSt suitablefor use in engine oils made according to SAE J300 in 0W-, 5W-, or 10W-grades.